Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films

Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films Kasra Shiva, Adel Soleimani, Jalil Morshedian, Farhid Farahmandghavi, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4548087/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In this research, we prepared an antibacterial packaging composite film for food packaging. Ajwan essential oil (AEO) was adsorbed onto chitosan (CS) particles, which were loaded in a combination of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene graft-maleic anhydride (PEma, 4%). Gas chromatography (GC) results confirmed successful AEO adsorption on chitosan particles, with protection from evaporation during the film formation process. Additionally, inhibition zone (IZ) tests demonstrated increased antibacterial activity in the film. Mechanical tests revealed that AEO incorporation decreased tensile strength but increased elongation at break, while CS reduced elongation at break. CS particles in PE-7.5-0 (910 cm³/m²·day·bar) reduced oxygen permeability compared to PE-0-0 (1680 cm³/m²·day·bar), but adding AEO increased oxygen permeability (PE-0-10, 2200 cm³/m²·day·bar). The antibacterial activity results indicated a synergistic inhibitory effect of CS and AEO. The composite film containing 7.5% chitosan and 10% adsorbed AEO (PE-7.5-10) exhibited suitable mechanical properties and improved antibacterial behavior due to AEO adsorption on CS. Consequently, it can be considered a suitable candidate for food packaging. Antibacterial Packaging Low-density polyethylene Chitosan Ajwain Essential oil Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1 Introduction Food products mainly classified as perishable products, suffering from short shelf life. Furthermore, they are vulnerable to chemical reactions and bacterial contamination, and their quality may deteriorate during production, processing, transportation, and storage stages [ 1 ]. Along with the growing demand for healthy, less processed, and high-quality foods, these challenges are the driving force behind some dynamic changes in the food packaging industry [ 2 ]. Among the polymers used in food packaging, polyolefins such as polyethylene (PE) and polypropylene (PP) are preferred for several reasons such as low cost, flexibility, chemical inertness, recyclability, good processability, non-toxicity, and biocompatibility. Since these polymers have very good sealing properties, they are also used as a bonding layer on aluminum foil when applying different polymers on the foil. Although LDPE is a good barrier against moisture, it is relatively permeable against oxygen and is considered a weak barrier against odors. Polyethylene also cannot limit the migration of microbes from the paper or mineral-coating pigments on the paper to the packaged food. These weak features make the use of this polymer challenging in food packaging applications and need to be improved. To improve the mechanical properties of LDPE, it is blended with linear low-density polyethylene (LLDPE), so it can better withstand the strain of transportation [ 3 , 4 ]. Passive traditional food packaging techniques, involves the use of a covering material, which only act as a barrier to postpone harmful environmental effects, and cannot guarantee food protection and quality [ 5 ]. As a result, a switch from the standard conception of packaging to minimize the interaction between food and packaging material to a novel view emphasizing the favorable effects of some food/package interactions seems inevitable. A most recent alternative with promising potentials in this field is active packaging, as a system with ability of changing conditions of the wrapped products, which can enhance the preservation of properties, provides better safety, prolongs shelf-life, and protect the quality of foods [ 6 ]. Among different sorts of active packaging, the antibacterial types are the most innovative concepts in the food industry. These systems intermingle the protective features of antibacterial agents with preservative characteristics for foods[ 7 – 9 ]. In direct use of antibacterial agents in foods have a reasonably large antibacterial effect, due to quick diffusion of antibacterial component into the bulk. however, adverse effects of antibacterial agents such as food denaturation and off-flavoring may also occur. Therefore, the use of antibacterial agents within the package film matrix could be useful for a gradual and steady liberation over a long time. thus, the antibacterial effect could have been sustained over a long period of time[ 9 , 10 ]. Another solution to achieve the desired antibacterial activity is provided through indirect contact between food and antibacterial agent, by direct use of antibacterial compounds in the film package [ 4 , 11 – 14 ]. Using antibacterial agents in polyethylene food packaging systems have already been evaluated such as Thymol, Potassium sorbate, Nisin, Hexamethylenetetramine, organic acid and chitosan/essential oil [ 15 – 21 ]. In addition, among indirect methods, using oxidizing ions such as copper or silver ions as antibacterial agents in food packaging systems, have already been evaluated. But they should be consumed optimally because of their potential for toxicity. Meanwhile, a tremendous rise in bacterial resistance to antibiotics has increased the global trend towards using natural additives - such as essential oils (EOs) – in the food packaging industry. Natural extracts such as EOs and their constituents possess the GRAS (Generally recognized as safe) status by the US Food and Drug Administration (FDA) [ 22 ]. They also have been classified by the European Decision 2002/113/EC (Commission Decision 2002/113/EC) as flavorings [ 23 ]. In this sense, packaging producers and consumers consider the impregnation of polymeric plastic films by these agents as an attractive method to avoid bacterial food contaminations. Generally, there are different natural chemical compounds capable of antibacterial activity [ 24 , 25 ], including terpenoids and sesquiterpenes with various aliphatic hydrocarbons, aldehydes, acids, alcohols. Thymol is the main constituent of Trachyspermum ammi, also known as Ajwain, and can be extracted between 35 to 60% from the plant [ 26 ]. The non-thymol fraction includes para-cymene, Gamma-terpinene, Alpha-pinene, carvacrol, and other minor constituents [ 27 ]. Thymol is a predominant monoterpene phenolic compound which has been used as a food preservative for many years. With a wide range of antibacterial activity, thymol is capable of a high potential for perishable foods' safety and prolongs shelf life [ 28 ]. Thymol and carvacrol, which are isomers, are hydrophobic compounds that can easily dissolve in the hydrophobic domain of the bacterial cytoplasmic membrane and the lipid acyl chains, leading to a noticeable effect on the membrane and its functional and structural properties. although many studies have so far demonstrated the antibacterial activity of EOs and their active components against a wide range of pathogenic bacteria [ 29 – 32 ], only a few articles have focused on the use of EOs as additives in polymeric plastic films used for food packaging [ 33 – 35 ]. Min et al. used thymol as antibacterial agent and introduced a composite of THY@PCN/PUL/PVA nanofibers and claimed that the composite has the ability of sustained release of thymol as dual-antibacterial activity to prolonged the shelf life of fruits. Although it is not clear whether the use of Pullulan in packaging is economical or not [ 36 ]. Among active biopolymers, chitosan (CS) is of great interest in the food industry due to its unique properties such as antibacterial activity, biodegradability, biocompatibility and non-toxicity. CS, the linear and partly acetylated (1–4)-2-amino-2-deoxy--d-glusan, can be easily derived from chitin, the second most abundant natural polymer, found in crab, shrimp, lobster, coral, jellyfish, mushroom, and fungi [ 37 , 38 ]. It had been proven that CS is capable of absorbing oils and hydrophobic compounds on its surface [ 39 ]. Bi, J., et al. claimed that CS-graft-PVA film had a potential ability to be applied as a carrier to bind quantities of procyanidins to prepare an active food packaging, that the procyanidin encapsulation efficiency is over 95% and long-term release sustainability [ 40 ]. The lack of interest in this field may be because essential oils and their compounds are heat and shear-sensitive components, so, can quickly decompose or evaporate under high processing temperature and pressure. To overcome this problem, some researchers have used innovative methods. Nestro et al. fabricated active films based on ethylene-vinyl acetate (EVA) incorporated with 3.5 and 7% carvacrol or cinnamaldehyde by minimizing the mixing time and placing the material in the liquid nitrogen bath immediately after mixing to prevent any further evaporation of the antibacterial additive [ 41 ]. Solano et al. produced LDPE films with 1 and 4% Origanum vulgare and Thymus vulgaris using a single screw extruder. From the feed zone to die, the temperature profile was increased gradually to preserve the antibacterial additive from evaporation[ 42 ]. A mixture of LDPE and EVA was chosen to enhance the solubility and to ensure partial adhering of the EOs in the polymer matrix. The relatively higher retention of EOs in the film with is capable by higher concentration and lower polarity [ 43 , 44 ]. Guarda et al. coated corona-treated bi-axially oriented PP films with microcapsules containing thymol and carvacrol as natural antibacterial agents [ 45 ]. Esmaili and Asgari presented a method in which Carum copticum essential oil (CEO) encapsulated in CS nanoparticles. In the method, encapsulation of CEO in the particles was performed by an emulsion-ionic gelation with creating of crosslinking using pantasodium tripolyphosphate (TPP) and sodium hexametaphosphte (HMP), separately [ 46 ]. The aim of this research is to use Ajwain essential oil (AEO) in polyethylene-based food packaging films as an antibacterial agent. As explained AEO is sensitive to the environmental conditions and evaporates at the elevated temperature required to prepare polyethylene films, so, the main challenge of this research is to solve this problem. We decided to use the surface adsorption of AEO on chitosan particles to preserve it in the harsh conditions and high temperature of the process, which is a very efficient and simple method. To the best of our knowledge no research yet has been accomplished the adsorption of AEO molecules on CS particles in antibacterial food packaging systems. To improve the distribution of CS chains in the LDPE-LLDPE matrix, PE-graft-maleic anhydride (PE ma ) was used as a compatibilizer [ 47 , 48 ]. The innovation of this research is the use of CS particles (2.5-7% w/w) as an active carrier for Ajwain essential oil (AEO) to minimize its evaporation during the melt processing and enhance the thermal stability of the absorbed active oil. 2 Materials and methods 2.1 Materials The polymers used in this study were LDPE and LLDPE purchased from Amir Kabir Petrochemical Industry, Iran, with 209AA and 2420F, respectively, and PE ma was from Karangin, Iran. The antibacterial agent was AEO supplied from Barij Essence Co., Iran. Powdered CS was obtained from Bio Basic, Canada, CAS 9012-76-4, high MW, with at least deacetylation of 90% and dried at 100°C for 5 hours before use. Ethanol, decane, and acetone were purchased from Merck, Germany, and utilized as received. 2.2 Methods 2.2.1 Pellet preparation 960 grams (g) of LDPE and LLDPE (with a mass ratio of 70/30) was pre-mixed with 40 g of PE ma and fed to a twin-screw extruder (Brabender, ZSK-25, Germany) with an L/D ratio screw of 40 and a screw speed of 250 rpm with a feeding rate of 2 kg/hr. The temperature was 215°C (all zones). By passing through the extruder and because of shear and pressure forces, all materials were thoroughly mixed. As a result of passing through a basin of cold water, the molten material was left in string form, forming in granule shape using a pelletizer machine. 2.2.2 AEO adsorption on CS particles First, CS particles with a particle size of less than 108 microns were placed in an oven at 70°C for 5 hours to dry. 100 µL of AEO, dissolved in 3.5 mL of acetone, in 10 mL test tubes. Then 0.5 g CS was gradually added to the tubes. The tubes were sealed and located in a water bath and equilibrated at ambient temperature. Solid particles were separated from the mixture after 30, 60, 90, 180, 360, and 720 min by centrifugation at 5000 rpm (Sigma 2K15C refrigerated centrifuge, Sigma, England) for 5 minutes. The amount of AEO absorbed on CS particles was characterized and quantified according to the following method. Decane solution (2 mL, 120 ppm in acetone) as internal standard was added to 2 mL of the solution, and the mixture passed through a syringe-head Teflon filter (Spartan 0.2 µm, Whatman, England) and injected into gas chromatography-mass spectroscopy (GC- Mass) equipment. The concentration of each of the components was determined according to Eq. ( 1 ). $$\frac{{AUCIS}}{{AUCAEO's{\text{ }}Component}}=\frac{{CIS}}{{CAEO's{\text{ }}Component}}$$ 1 AUC IS and AUC EO’s components are the signals area for decane solution (internal standard) and any specific component of the AEO, respectively. C IS and C AEO’s components represent the concentration of decane and the specific AEO’s component, respectively. The AEO absorbed amount on CS ( n absorbed ) was calculated by subtracting amount of AEO’s components in the supernatant ( n supernatant ) from the initial AEO’s components ( n blank ) in control sample (Eq. ( 2 )). $$n{\text{adsorbed}}=n{\text{blank}}-n{\text{supernatant}}$$ 2 2.2.3 AEO/CS contact time Three samples containing 3 gr of CS and different amounts of AEO (2, 3 and 4 gr), were prepared in three separate beakers. CS particles followed by a contact time of 6 h at room temperature to complete the process of adsorption. The optimum contact time was determined using GC-Mass analysis. The mixture was later mixed with PE granules in an internal mixer. 2.2.4 Film preparation Prepared granules were blended with different amounts of AEO and/or CS and AEO-absorbed CS particles by melt mixing in a batch mixer (Brabender w-50, Germany). Initially, the granules were fed to the mixer at a temperature of 115°C and a rotor speed of 100 rpm. After melting for 3 min, the rotational speed decreased to 60 rpm (to protect the active oil compounds from oxidation and evaporation), and AEO, CS, or a mixture of both of them were added and to minimize the evaporation, the blending process continued for no longer than 2 min. The resulting melt mixed blends were hot-pressed for 1 min at 140°C under 150 bars using an electrically heated hydraulic press to obtain approximately 120 µm thick films. The antibacterial films developed with this method were immediately wrapped in aluminum foil and stored in plastic bags at 0–3°C for up to 1 week before their final use. Different formulations prepared in this research are presented in Table 1 . The samples were named Polyethylene-A-B where A and B present the percentages of the chitosan and essential oil, respectively. It should be noted that all samples contain 4%w/w of PE ma . Table 1 Formulations of the prepared samples Sample CS % (w/w) AEO % (w/w) PE ma % (w/w) LDPE + LLDPE % (w/w) PE-0-0 - - 4 96 PE-2.5-0 2.5 - 4 93.5 PE-5-0 5 - 4 91 PE-7.5-0 7.5 - 4 88.5 PE-0-5 - 5 4 91 PE-0-7.5 - 7.5 4 88.5 PE-0-10 - 10 4 86 PE-2.5-10* 2.5 10 4 93.5 PE-5-10* 5 10 4 91 PE-7.5-5* 7.5 5 4 87.5 PE-7.5-7.5* 7.5 7.5 4 87.5 PE-7.5-10* 7.5 10 4 87.5 *The samples prepared by mixing the LLDPE, LDPE and PE ma with AEO-absorbed CS particles 2.3 Characterization Structural characterization of the samples was done by FTIR. AEO and CS were separately mixed with KBr powder and then pressed into pellets for FTIR spectroscopy. Films with different formulations were cut into 2 * 2 cm 2 samples and were fixed to a sample holder on a Bruker, Equinox 55, Germany. We recorded 16 scans at a resolution of 4 cm − 1 for each spectrum. Measurements were recorded from wave number 400–4000 cm − 1 . The amount of AEO in the samples was determined by GC-Mass. Five grams of the film samples were cut and extracted for about 24 h by Soxhlet extraction using 200 mL ethanol. One µl aliquot of the extracted solution was characterized by Agilent 6890, USA (GC), and Agilent 5973, USA (MS) equipped with a fused silica capillary column (HP-5 MS). Primary column temperature was 50°C and heating rate of 5°C min − 1 applied until 220°C, then kept this temperature for 4 min before sampling; split ratio, 1:100; carrier gas, helium and a decane solution (2 mL, 120 ppm in acetone) was used as an internal standard. Also, AEO was analyzed by GC-MS technique. 10 µL of AEO was diluted by 2 mL ethanol, and the resulting solution (0.5µL) was injected for the GC-MS test while the condition mentioned above was applied. Adsorption of AEO constituents on CS particles after different contact times (1, 1.5, 3, 6, 12 hrs.) was also determined by GC-Mass analysis. By absorbing AEO constituents on CS particles, their concentration decreased after specific intervals. The quantification of GC-Mass test results is based on comparing the area below the peak related to decane with the peaks of AEO components. Normalized data was achieved by dividing the absorbed amount for each constituent by its percentage. The crystal structure analysis of the samples and CS powder was performed using XRD. X-ray diffraction (XRD) patterns were obtained by using a SIEMENS, D5000 (Germany) with a detector operating (voltage = 40 kV, current = 40 mA) with Cu kα radiation. The scanning speed was 1.2 °/min, and the scanning scope of 2Ɵ was 5–80°. To study the effect of AEO and/or CS on polymer mechanical properties, tensile strength and elongation at break of the samples were evaluated. Samples were cut lengthwise and cross direction 115*19 mm according to the ASTM D-638 method. The strips were mounted and clamped with pneumatic grips on a universal testing machine SANTAM, STM-20, with an initial grip distance of 30 mm. The rate of grip separation was 50 mm/min with a load cell of 1000 N and measurements were performed on 5 replicates for each sample. The gas barrier properties were represented by the oxygen transmission rate (OTR). Measurements were carried out by using a GDP-C gas permeability tester (Coesfeld Meterialtest, Germany) according to ASTM D 1434. Each film sample was 14 cm in diameter, and measurements were carried out at 23°C and 50% RH. The thermal stability of the films was monitored using a thermogravimetric analyzer (TOLEDO, METTLER, Switzerland). By recording thermogravimetric data, the film samples' mass-loss curves vs. temperature were obtained. All the experiments were performed at a heating rate of 10°C min − 1 and inert nitrogen atmosphere in the temperature range 25–600°C. SEM was used to study the morphology of fracture surfaces. The cross-section morphology of the samples was investigated by TESCAN model VEGA, the Czech Republic scanning electronic microscope, using an accelerating voltage of 5–30 kV. The samples were immersed in liquid nitrogen for 1 min and fractured to analyze the cross-section. The samples were sputter-coated with the gold layer before analyzing to avoid electrostatic charging under the electron beam and increase electrical conductivity. The antibacterial activity of polymeric films containing AEO and/or CS was evaluated quantitatively against two food spoilage bacteria, including Gram-negative bacteria, Escherichia coli (E.coli) and Gram-positive bacteria, Staphylococcus aureus (S.aureus). Virgin film without AEO and CS was included as controls. The bacterial strains selected here representing typical spoilage microorganisms widely occurring in various types of food products. The antibacterial activity of active films was determined using the agar disc diffusion assay. Polymeric films were cut into disc whit 1 cm diameter and placed in the middle of the Petridishes containing nutrient agar purchased from Merk, Germany. From each inoculum (10 6 CFU/mL), 0.1 mL was spread onto the plate medium. Then, the Petri dishes were placed in an incubation chamber at the appropriate conditions (37°C for 24 h). The antibacterial activity of each sample was determined by observing the clear zone of the targeted microorganisms around the active films. The diameter of the zone was measured by a digital micrometer and recorded as the ratio of the zone of inhibition area to the sample area. Mueller Hinton Agar medium was used for determining antibacterial activity. The test was carried out in duplicate for each formulation. The inhibitory activity against E coli and S. aureus was evaluated by measuring the diameter of the transparent inhibition zone, and the antibacterial effect was evaluated by comparing inhibition zone diameters The average and standard deviation of two measurements were calculated. 2.4 Statistical Analysis Data points were presented as the mean of the measured values. The data were exposed to an analysis of variance (ANOVA) at the level of significance at p < 0.05 using the Originlab 2022 software package. Statistical procedure was resolved by means of confidence intervals using Tukey’s test. 3 Results and discussion 3.1 Characterization of essential oil 3.1.1 GC-Mass Analysis GC-Mass results of AEO are shown in Table 2 (GC-Mass chromatograms ( Figure S1 ) is in the supporting information). According to the results, different constituents were identified using their retention time indices and mass spectra fragmentation from the Nist and Wiley library, examining the fragmentation profiles and comparing them with those described in the literature. Thymol (47.34%w/w), ρ-cymene (28.59%w/w), and \(\gamma\) -terpinene (16.24%w/w) were the main constituents which more than 92%w/w of the AEO components was related to them, followed by carvacrol (1.27%). Basij et al. also described thymol, ρ-cymene, and \(\gamma\) -terpinene as the major compounds of AEO with 90–97% of the total components [ 49 ]. It is worth noting that ρ-cymene and \(\gamma\) -terpinene are the main precursors for thymol and carvacrol biosynthesize hence, high levels of these two components result in the high thymol percentage in AEO. Table 2 GC-Mass results of AEO. RT Area (%) Library/ID AEO component Structure 10.17 28.59 Benzene,1-methyl-2-(1-methyl) ρ-cymene 11.18 16.24 1,4-cyclohexadiene, 1-methyl-4-(1-methylethyl) \(\gamma\) -terpinene 18 47.34 Thymol thymol 18.15 1.27 3-Methyl-4-isopropylphenol carvacrol 3.2 AEO adsorption on CS The dependence of AEO physical adsorption on CS with time[ 50 , 51 ] was used to find the optimum contact time between AEO and CS particles. GC-Mass chromatograms of samples with different contact times are presented in Supporting information ( Figures S2 – S4 ). It is obvious that, there are significant differences between peaks and their intensity in different samples. Since there are three major constituents in the AEO (thymol, ρ-cymene, and \(\gamma\) -terpinene), the variation in the adsorption of these components was evaluated (based on the literature [ 52 ]). Figure 1 A shows the adsorption of different constituents on CS at different time intervals. Since, absorbed AEO amounts directly influence the corresponding adsorption of each constituent, the graph was normalized (Fig. 1 B). So, adsorption is a selective process, and CS particles' tendency for thymol uptake is more evident compared to ρ-cymene and \(\gamma\) -terpinene. Theoretical results[ 53 ] (Eq. ( 3 ) and As it is clear from Table 3 , (solubility parameters were obtained according to the Van Krevelen et al. book 53 ) the total dissolution variable (δTotal) for the 3 dominant components of Ajwan essential oil varies from 32.39 for thymol to 10.32 for \({\gamma }\) -terpinene. The partial dissolution variable of dispersion (δD) has the largest contribution to the total dissolution variable, which indicates the lipophilic nature of essential oil components. The lowest dispersion partial dissolution variable is 32.08 for \({\gamma }-\text{t}\text{e}\text{r}\text{p}\text{i}\text{n}\text{e}\text{n}\text{e}\) and the highest is 36.59 for thymol. On the other hand, polar (δP) and hydrogen (δH) partial dissolution variables have the least contribution to the overall dissolution variable. The lowest partial polar dissolution variable for \({\gamma }-\text{t}\text{e}\text{r}\text{p}\text{i}\text{n}\text{e}\text{n}\text{e}\) is 0.92 and the highest is 2.39 for thymol. The partial hydrogen dissolution variable for ρ-cymene and \({\gamma }-\text{t}\text{e}\text{r}\text{p}\text{i}\text{n}\text{e}\text{n}\text{e}\) is zero, and the highest is 14.20 for thymol. As can be seen in Table 3 , the value of \(\varDelta {{\delta }}_{\text{i}.\text{j}}\) for the three constituent components of AEO essential oil is close to each other, and it can be expected that the affinity of these three components to be absorbed on chitosan is close to each other and similar adsorption is expected for these components on chitosan. According to the theory, three components should be absorbed almost equally, but due to the higher molecular weight, density and boiling point of Thymol compared to the other components, the thymol is more absorbed. Table 3 ) further anticipated a close adsorption amount for different constituents. The dissolution between soluble component i and solvent j ( \(\varDelta {\delta }_{i.j}\) ) is calculated from Eq. ( 3 ): $$\varDelta {\delta }_{i.j}=\sqrt{4{\left({\delta }_{D}^{i}- {\delta }_{D}^{j}\right)}^{2}+{\left({\delta }_{P}^{i}- {\delta }_{P}^{j}\right)}^{2}+{\left({\delta }_{H}^{i}- {\delta }_{H}^{j}\right)}^{2}}$$ 3 In which, dispersion forces ( \({\delta }_{D}\) ), intermolecular dipole forces (dipole interactions) ( \({\delta }_{P}\) ) and energy of hydrogen bonds between molecules ( \({\delta }_{H}\) ) should be calculated. The smaller \(\varDelta {\delta }_{i.j}\) is, the greater the affinity between solvent and solute. To estimate \({\delta }_{D}\) , \({\delta }_{P}\) and \({\delta }_{H}\) , a method based on the structural participation of functional groups was used. In this way, \({\delta }_{D}\) is calculated from the Eq. ( 4 ): $${\delta }_{D}= \frac{\sum {F}_{D}}{{V}_{m}}$$ 4 Where, \({F}_{D}\) is the dispersion component of molar absorption constant. If the substance has only one polar group, \({\delta }_{P}\) can be calculated from the relation \({\delta }_{P}= \frac{{F}_{P}}{{V}_{m}}\) , but for more than one polar group, it is necessary to calculate the interactions of polar groups with the help of the Eq. ( 5 ): $${\delta }_{P}= \frac{\sqrt{\sum {F}_{P}^{2}}}{{V}_{m}}$$ 5 Where, \({F}_{P}\) is the polar component of molar adsorption constant. Although the F method is not directly applicable in the calculation of \({\delta }_{H}\) , but Birbauer and Hansen assumed that the hydrogen bonds are additive, which led to the Eq. ( 6 ): $${\delta }_{H}= \sqrt{\frac{\sum {E}_{H}}{{V}_{m}}}$$ 6 where \({E}_{H}\) is the hydrogen bond energy for each structural group ( \({F}_{H}{V}_{im}\) ). As it is clear from Table 3 , (solubility parameters were obtained according to the Van Krevelen et al. book [ 53 ]) the total dissolution variable (δ Total ) for the 3 dominant components of Ajwan essential oil varies from 32.39 for thymol to 10.32 for \(\gamma\) -terpinene. The partial dissolution variable of dispersion (δ D ) has the largest contribution to the total dissolution variable, which indicates the lipophilic nature of essential oil components. The lowest dispersion partial dissolution variable is 32.08 for \(\gamma\) -terpinene and the highest is 36.59 for thymol. On the other hand, polar (δ P ) and hydrogen (δ H ) partial dissolution variables have the least contribution to the overall dissolution variable. The lowest partial polar dissolution variable for \(\gamma\) -terpinene is 0.92 and the highest is 2.39 for thymol. The partial hydrogen dissolution variable for ρ-cymene and \(\gamma\) -terpinene is zero, and the highest is 14.20 for thymol. As can be seen in Table 3 , the value of \(\varDelta {\delta }_{i.j}\) for the three constituent components of AEO essential oil is close to each other, and it can be expected that the affinity of these three components to be absorbed on chitosan is close to each other and similar adsorption is expected for these components on chitosan. According to the theory, three components should be absorbed almost equally, but due to the higher molecular weight, density and boiling point of Thymol compared to the other components, the thymol is more absorbed. Table 3 Molar volume and partial solubility variables of essential oils of Ajwain and chitosan. component Molar volume (cc/mol) \({\delta }_{H}\) \(\left({MPa}^{1/2}\right)\) \({\delta }_{P}\) \(\left({MPa}^{1/2}\right)\) \({\delta }_{D}\) \(\left({MPa}^{1/2}\right)\) \({\delta }_{Total}\) \(\left({MPa}^{1/2}\right)\) \(\varDelta {\delta }_{i.j}\) with chitosan thymol 99.211 14.20 2.39 36.59 39.32 42.93 ρ-cymene 107.877 0 1.02 32.91 32.92 42.15 \(\gamma\) -terpinene 119.999 0 0.92 32.08 32.10 40.83 Chitosan 302.080 24.07 5.54 15.76 29.30 - Figure 1 testify that 6 h is the optimum time for AEO uptake by CS particles. It is worth mentioning that the physical interaction between CS particles and AEO retains the AEO molecules in the film during the processing. 3.3 Characterization of the LDPE/LLDPE/CS/AEO loaded films 3.3.1 FTIR analysis FTIR spectra of the individual components are shown in Fig. 2 . The spectrum of CS powder displays an accentuated absorption peak at 3444cm − 1 , showing the stretching vibration of –(NH 2 ) and –(OH) as well as inter and intramolecular hydrogen bonding. The peak at 2861cm − 1 is due to –(CH) asymmetric stretching vibration. The peak around 1650 cm − 1 corresponds to the carbonyl group, which shows the acetylated amino groups of chitin, indicating an incomplete deacetylation process of the CS [ 54 , 55 ]. Peaks at 1656 cm − 1 and 1596 cm − 1 for carbonyl stretching vibration (amide-1), N-H stretching vibration (amide-2), respectively correspond to the amide linkages [ 56 ]. The peaks at 1382 cm − 1 and 1035 cm − 1 are assigned to the saccharide and –(C-O-C)- stretching vibration of glucosamine ring, respectively [ 57 ]. The neat polyethylene spectrum shows a hydrocarbon stretching peak around 2848-2913cm − 1 . The peaks of 1467 cm − 1 and 717 cm − 1 correspond to the methylene scissoring and methylene rocking vibrations, respectively [ 47 ]. In the case of PE-5-0 spectrum, widening in 3700 and 3000 cm − 1 due to CS addition is shown. The depicted peak at 1035 cm − 1 is attributed to the vibration of –(C-O-C)- groups in CS. As AEO is a mixture of different components, FTIR can only detect different functional groups but not the constituents. The spectrum exhibits a peak at 3421cm − 1 attributed to hydroxyl –(OH) stretching vibration groups of phenolic compounds[ 56 ]. The absorption peaks at 2960-2867cm − 1 are assigned to the symmetric and asymmetric stretching (C-H) groups. The spectrum from 1400–1500 cm − 1 shows the C-H sp 3 bending and stretching vibration of the aromatic ring. The peak around 1149 cm − 1 indicates meta-substitution for thymol. The peaks 1087 and 1289 cm − 1 attributed to the thymol component. The absorption peaks at 1056 and 1513cm − 1 are assigned to the para-substitution and C-H(CH 3 ) waging of p-cymene. The peaks at 860, 1170, and 1250 attribute to carvacrol—the peak at 1619 cm − 1 assigned to the aromatic ring [ 58 ]. The peak at 805–810 cm − 1 is because of plane alkene C-H stretching [ 7 ]. PE-0-10 spectrum exhibits the characteristic bands of the polymer matrix and those of AEO simultaneously. The peaks representing the polymeric matrix could be seen at 2884–2913, 1467, and 717 cm − 1 . Since the observed peaks in the FTIR spectrum is the sum of the absorption of polymer matrix and AEO bonds, widening between 2848–2960 cm − 1 is due to overlapping bands assigned to stretching frequency of –(CH 3 ) groups in AEO and polymer matrix. The characteristic peaks of AEO could be observed at 3421, 1289, 1149, and 1056 cm − 1 which was already explained. 3.3.2 AEO Loaded films After optimizing the time required to absorb AEO on CS, AEO-absorbed CS particles were mixed with PE, and the films were prepared as mentioned before, then the extraction of the remaining of AEO from the films was done. The extracted solution was injected into the GC-Mass after addition of decane. The results of the experiment are given in Table 3 as examples for two samples. The relevant chromatograms can be seen in Supporting information (Figures S5-S6). Table 4 Gas chromatographic results of the PE-0-10 and PE-7.5-10 samples. Sample Retention time (min) Chemical composition Percentage of the components (%) Component weight per gram of film (mg/g) PE-7.5-7.5 9.297 Decane (standard) 0.502 - 10.043 ρ-cymene 8.461 2.792 11.086 \(\gamma\) -terpinene 4.613 1.545 17.884 thymol 83.359 30.792 18.114 carvacrol 1.393 0.514 PE-7.5-10 9.291 Decane (standard) 0.597 - 10.037 ρ-cymene 1.842 0.892 11.080 \(\gamma\) -terpinene 0.826 0.406 17.890 thymol 78.498 42.591 18.114 carvacrol 1.449 0.677 Figure 3 shows different component amounts of AEO loaded in the samples. Figure 3 A indicates extracted AEO in milligrams per gram of each film. As seen in the Fig. 3 , the AEO loading amount is significantly higher in CS containing films and by increasing the amount of CS, the percentage of absorbed AEO increases. It could be attributed to the tendency of CS to the oil adsorption and high aspect ratio of the powder [ 59 , 60 ]. The results shown in Fig. 3 , reveal two important points. First, the presence of CS reduces oil evaporation during the film formation. Second, among the components of AEO, thymol evaporates less than para-cymene and gamma-terpinene, indicating that CS absorb more thymol in comparison with the others. This test provided a similar result regarding AEO adsorption on CS. In addition, the molecular weight of thymol is higher than para-cymene and gamma-terpinene. The simultaneous effect of these two factors causes the high thymol content in the samples. It should be noted that the above reasons are also valid for carvacrol, but owing to low percentage of this component, it does not have much effect on the final properties of the film. Considering that the samples containing 2.5 and 5% chitosan and 10% AEO (samples PE-2.5-10 and PE-5-10 in Table 1 ) have absorbed a smaller amount of essential oil than the PE-7.5-10 sample, so other tests were continued on the sample containing 7.5%w/w chitosan. 3.3.3 XRD analysis X-ray diffraction testing is commonly used to identify the crystalline or amorphous structure of materials based on their diffraction patterns and provide documentary evidence to describe polymorphic structures. The XRD pattern of the polymer, CS, and the composite samples are shown in Fig. 4 . As can be seen in Fig. 4 A, the XRD pattern of CS illustrates two peaks at 2θ of 10.63° and 19.8°, were assigned to the (110) and (200) lattice planes, typical fingerprints of semi-crystalline CS which is in agreement with the results presented in the literature [ 61 – 63 ]. The high degree of crystallinity of CS is attributed to a large quantity of hydroxyl and amino groups which are able to form strong intermolecular and intramolecular hydrogen bonds [ 61 ]. As it can be seen in the XRD pattern of PE-0-0, two peaks at 2θ of 21.41 and 23.70 were assigned to the (110) and (200) lattice planes. In Fig. 4 A, the XRD pattern of PE/CS with different compositions, no obvious peak observed for chitosan. The result confirms that CS was exfoliated in the polymer matrix. Furthermore, the CS content has no significant effect on the crystal size of PE. As shown in Fig. 4 B, the addition of different amounts of AEO did not have a remarkable effect on the crystalline structure of the films. Esfandiari et al. and Suppakul et al. produced LLDPE and LDPE films containing Rosemary essential oil and 1% linalool or methyl chavicol. They found no significant difference in the crystalline structure of the oil loaded films with pure LLDPE or LDPE [ 64 , 65 ]. Therefore, it can be concluded that the presence of CS and AEO up to 7.5% and 10%, respectively, does not have a significant effect on the crystal structure of the polyethylene films. 3.3.4 Mechanical properties Packaging films need proper mechanical strength and impact resistance during transportation and handling. In order to study the mechanical properties of the prepared films, a tensile test was performed on them. Tensile strength and elongation at break of different samples are shown in Table 4 . The elongation at break and tensile strength (PE-5-0 and PE-7.5-0) were decreased significantly by adding CS concerning PE-0-0 (P < 0.05). The Youngs modulus of PE-5-0 and PE-7.5-0 has improved by the introduction of CS particles compared to PE-0-0 (P < 0.05), due to the rigidity of CS molecules added to the polymer matrix which leads to restrict polymer chains' mobility [ 66 , 67 ]. In addition, improper distribution of CS can be a factor in reducing tensile strength, as CS aggregation can cause film failure even at low stresses[ 44 ]. Furthermore, thermodynamic immiscibility (weak interfacial adhesion) and intrinsic incompatibility of the polymer chains and CS particles causes decrease in elongation at break as well as tensile strength [ 47 , 54 , 64 , 68 ]. Compared to PE-0-0, AEO loading also reduces the tensile strength and the young modulus but increases the elongation at break of PE-5-0 and PE-7.5-0 (P < 0.05). This decrease could be attributed to the AEO discontinuities in the polymer matrix that acts as plasticizer [ 69 ]. It means that at low concentrations of AEO, it has discontinuous structure as single droplets. The presence of AEO increases the possibility of polymer chains slippage on each other and, as a result, improves the flexibility and elongation of the films [ 43 , 70 , 71 ]. For the samples mixed with AEO and CS, compared to PE-0-0, a decrease in the tensile strength and the young modulus is observed (P < 0.05). However, in PE-7.5-10 sample, by increasing the amount of AEO and the possibility of proper wetting of chitosan, which helps its better distribution in the film, the tensile strength was improved. Table 5 The effect of incorporation of CS and AEO on the mechanical properties of the samples. Sample Tensile Strength (MPa) Elongation at break (%) Modulus (MPa) PE-0-0 16.3 ± 0.6 879 ± 35 241 ± 3.0 PE-2.5-0 15.1 ±0.5 701 ± 48 247 ± 2.2 PE-5-0 13.4 ± 0.6 601 ± 43 268 ± 4.1 PE-7.5-0 12.5 ± 0.8 527 ± 44 291 ± 8.7 PE-0-5 13.6 ± 0.4 906 ± 41 211 ± 5.0 PE-0-7.5 11.9 ± 0.5 1038 ± 51 201 ± 8.3 PE-0-10 10.2 ± 0.6 1069 ± 35 175 ± 5.5 PE-7.5-5 12.1 ± 0.7 753 ± 23 260 ± 5.8 PE-7.5-7.5 13.0 ± 0.4 824 ± 27 223 ± 3.8 PE-7.5-10 14.4 ± 0.6 948 ± 31 214 ± 5.5 3.3.5 Oxygen transmission rate (OTR) To ensure complete protection of food, it is necessary to minimize the influence of factors that cause spoilage of food. From this point of view, oxygen permeability is one of the factors that can affect the shelf life of food. OTR analysis was carried out to determine the barrier properties of different samples to permeate oxygen (Fig. 5 ). The OTR value of the PE-0-0 was found around 1680 cm 3 /m 2 .d.bar. CS incorporation declined OTR values. At 2.5, 5, and 7.5%w/w CS, the OTR of the prepared samples was reduced to 1390, 1100, and 910 cm 3 /m 2 .d.bar, respectively. Chitosan particles in the polymer matrix are able to create a tortuous path that acts as a gas barrier. High tortuosity leads to higher barrier properties and lower permeability [ 72 ]. As can be seen, there was an increase in OTR values of AEO plastic-based samples compared to the PE-0-0, as shown in Fig. 5 . The incorporation of AEO increased OTR value to 1880 in PE-0-5 and 2064 cm 3 /m 2 .d.bar in PE-0-7.5 film. The rise in OTR values is not surprising owing to the alteration of film structure in the presence of AEO as a result of two interrelated causes[ 42 , 43 , 73 ]. AEO at first, because of its nature, could dissolve and migrate to the amorphous region of the film. Nevertheless, after saturation of the amorphous region, AEO starts to interpose with the polymer-polymer interactions, leading to an increase in the OTR property of the plastic films. Second, the plasticizing effect of the active oil causes an increase in the polymer chains mobility and consequently decreases the resistance of samples to oxygen diffusion. In the case of CS/AEO loaded samples, two opposing trends could be observed simultaneously. From one side, the presence of CS molecules restricts oxygen flow, and on the other hand, the rising free volume in the film structure as a result of chemical interaction between AEO and polymer chains reinforce oxygen permeability[ 74 ]. As can be seen, OTR values increased in all samples because of the predominating effect of AEO incorporation. 3.3.6 Thermal behavior Thermal stability is one of the important characteristics in packaging films as they may undergo heat processes within production, distribution, and storage[ 75 , 76 ]. In this study, this method was also used to determine the remaining AEO in the films after processing. Figure 6 A shows TGA thermograms of AEO, CS, PE-0-10 and PE-7.5-10. The result of the CS thermal degradation test, as mentioned in the literature, showed two separate weight losses[ 77 ]. The first weight loss step of about 5%, that takes place before 150°C, is related to the evaporation of the absorbed water. The main degradation was observed between 250 and 400°C, with a weight loss of about 50%. Hence, CS shows resistance to thermal degradation up to the processing temperatures. For the next steps and preparation of the compounds, CS was subjected to thermal treatment for 5 h at 70°C to remove the absorbed water. As shown in the Fig. 6 A, AEO is evaporated completely till 160 ºC. Figure 6 A for the sample PE-0-10 shows a two-step degradation process in the temperature ranges of 50–200 and 420–530°C which are related to AEO evaporation and polymer matrix degradation, respectively. The result indicates that at 160 and 250 ˚C more than 7% and almost all of AEO loaded in the film evaporates, respectively. Three distinct thermal degradation steps are detectable for the sample PE-7.5-10. The initial weight loss for temperatures less than 250°C is attributed to the volatilization of AEO and the second step related to the decomposition of CS. As a result of composite fabrication, the CS degradation temperature has increased from 250 to 290°C. The remarkable thing is that with the addition of chitosan to the system, the durability of AEO in the film increased and up to 200°C only about 3% of the oil was evaporated. The reason can be attributed to the surface adsorption of AEO on CS, which leads to more loading of the oil in the film. This data is in full agreement with the result of GC-Mass test. Therefore, the method of adsorption of AEO on CS particles can retain the essential oil more than the direct method of adding AEO and mixing with polyethylene granules in the final film. 3.3.7 Scanning electron microscopy (SEM) analysis Electron microscopic images of the cross-section of the samples containing the maximum values of CS and AEO, individually, and the both are shown in Fig. 6 B (1–3). Figure 6B1 illustrates the morphology of sample PE-0-10. The Fig. 6 B 3 shows a relatively continuous distribution of AEO in the polymer matrix. On the other hand, Fig. 6 B 2 indicates improper distribution of CS and its aggregations in the polymer matrix. While, with the help of wetting chitosan with the oil, the distribution of CS in the polymer matrix is ​​greatly improved, which is confirmed by the results of mechanical properties. 3.3.8 Antibacterial activity of the films Since the purpose of this research is to prepare antibacterial PE films for food packaging, the antibacterial test was performed on the samples containing the maximum amounts of AEO and CS, as well as the sample containing the both components. Antibacterial studies were conducted using the agar disc diffusion method, which presents a qualitative evaluation of the antibacterial properties of the samples. In this respect, when the polymeric films containing the antibacterial agent are placed on top of the culture media, it is expected that the active agent diffuse from the bulk of the film into the agar in a radial manner, developing a clear zone of growth inhibition surrounding the sample[ 73 ]. Typical results of these tests for different samples are presented in Fig. 7 . The ratio of the clear zone area to the sample area was adopted to show the antibacterial activity of the active films. As expected, the control sample (PE-0-0) did not exhibit antibacterial activity against any of the tested bacteria. Also, samples with 5 and 7.5% CS did not reveal antibacterial activity, and they showed neither inhibition nor retraction zone, because CS is enclosed in the polymer matrix and has no migration to the surface (physiochemical properties of CS) [ 78 , 79 ]. Further, Fig. 7 illustrates the inhibition zones of active films impregnated with AEO against tested microorganisms. The result indicates that sample PE-7.5-10 shows more antibacterial property than PE-0-10, it is due to the presence of CS in the sample, which causes less AEO evaporation from the composite during film production process by adsorption of AEO. The constituents of AEO, thymol and carvacrol, have polar functional groups[ 80 , 81 ], including hydroxyl groups which could probably interact with CS chains through hydrogen bond and improve the resistance of AEO against harsh processing conditions. These findings emphasize the crucial function of CS particles as active carrier of the volatile component of AEO. The antibacterial properties of EOs containing high levels of thymol and/or carvacrol have been described by many researchers[ 82 ], which is attributed to their ability to permeate and depolarize the cytoplasmic membrane. Thymol and carvacrol interact with the lipid bilayer of the bacterial cytoplasmic membrane led to a loss of integrity, releasing the lipopolysaccharides, and hence, increasing the permeability of the adenosine triphosphate in the cytoplasmic membrane, and consequently, change the passive permeability of the cell and leakage of the cellular material such as ions and nucleic acid[ 41 , 83 ]. Most authors have reported that Gram-negative bacteria are more resistant than Gram-positive ones using different EOs[ 84 ]. The higher resistance of Gram-negative bacteria to the antibacterial activity of EOs could be assigned to the external layer that encircles the wall of the lipopolysaccharides in these bacterial species, limiting the diffusion of hydrophobic constituents[ 45 ]. However, our findings revealed higher effectiveness of AEO against E. coli, which is categorized as Gram-negative bacteria. Other studies have reported the same result additionally[ 42 , 44 ]. Consequently, it can be concluded that experimental conditions for antibacterial analysis are vital to get high or low sensitivity of specific bacteria species against active compounds. 4 Conclusion The purpose of this study is to prepare antibacterial food packaging films based on AEO and improve the performance of the antibacterial agent by using chitosan as an absorbent. Characteristic parameters of the films such as mechanical properties, thermal stability, OTR and anti-bacterial activity have been successfully studied as well as chitosan's ability to absorb AEO. First, variation in the surface adsorption of three main components in AEO (thymol, ρ-cymene, and γ-terpinene) on chitosan was investigated. The optimal time for proper physical interaction between AEO and CS particles and anchoring of AEO molecules on chitosan was calculated about 6 hours. The results of TGA tests of the films prepared with maximum amounts of AEO, CS and the both, PE-7.5.0, PE-0-10, PE-7.5-10 showed that the presence of CS reduces the evaporation of oil (from 7% in PE-0-10 to 3% for PE-7.5-10) during the film formation process. In addition, the tensile test results show that after incorporation of AEO and CS, the modulus and tensile strength of sample PE-7.5-10 were 224 and 14.5 MPa, respectively, and the elongation at break was about 948%, which shows the films still has good mechanical properties for food packaging. The value of OTR for PE-7.5-10 sample was calculated 1500, while, the value for PE-0-0 measured 1680 cm 3 /m 2 .day.bar, which is a significant reduction. The consequence of antibacterial inhibition zone tests illustrates that the control sample, (PE-0-0 film), did not show antibacterial activity against any of the gram-positive (S. Aureus) and gram-negative (E. coli) bacteria, as well as PE-7.5-0 sample. Also, PE-0-10 exhibited relative resistance against E. coli and S. aureus bacteria, whenever, PE-7.5-10 sample showed high antibacterial resistance. The results emphasize the vital function of CS particles as active carriers of AEO volatile component. Therefore, it can be said that the sample containing the highest amounts of CS and AEO, due to its excellent antibacterial properties and acceptable mechanical properties, can be a good candidate for use in food packaging. Declarations Ethical Statements: Ethical approval: Not Applicable. Consent to participate: Informed consent was obtained from all individual participants included in the study. consent to publish: All the authors of manuscript declare their consent to print and publish the article. Funding: This work was supported by Iran Polymer and Petrochemical Institute (Grant No.23794109). Author Contribution Farhid Farahmand conceived of the presented idea. Farhid Farahmnad and Jalil Morshedian developed the theory and performed the computations. Kasra Shiva and Adel Soleimani verified the analytical methods. Farhid Farahmand encouraged Adel Soleimani and Kasra Shiva to investigate on the results of adsorption and supervised the findings of this work. Adel Soleimani took the lead in writing the manuscript. All authors discussed the results and contributed to the final manuscript. References Peng, B., et al.: Recent Advances in Nanomaterials-Enabled Active Food Packaging: Nanomaterials Synthesis, Applications and Future Prospects. Food Control, : p. 110542. (2024) Ganjeh, A.M., et al.: Recent advances in nano-reinforced food packaging based on biodegradable polymers using layer-by-layer assembly: A review. Carbohydr. Polym. Technol. Appl., : p. 100395. (2023) Nouri, M., et al.: Investigation of LLDPE/LDPE blown films by response surface methodology. (2006) Soleimani, A., et al.: Silver/Hydrogen-Exchanged Zeolites Embedded in Modified Polyethylene Blends for Antibacterial Packaging with Prolonged Color Stability. ACS Appl. Polym. Mater. 5 (4), 2917–2930 (2023) Yao, Q., et al.: Polysaccharide-based food packaging and intelligent packaging applications: A comprehensive review, p. 104390. Trends in Food Science & Technology (2024) Wang, K., et al.: Preparation and characterization of chitosan/dialdehyde carboxymethyl cellulose composite film loaded with cinnamaldehyde@ zein nanoparticles for active food packaging. Int. J. Biol. Macromol. 261 , 129586 (2024) Valderrama, A.C.S., De, G.C.R.: Traceability of active compounds of essential oils in antimicrobial food packaging using a chemometric method by ATR-FTIR. Am. J. Anal. Chem. 8 (11), 726 (2017) Nasution, H., et al.: Properties of active packaging of PLA-PCL film integrated with chitosan as an antibacterial agent and syzygium cumini seed extract as an antioxidant agent. Heliyon, 10 (1). (2024) Kola, V., Carvalho, I.S.: Plant extracts as additives in biodegradable films and coatings in active food packaging. Food Bioscience, : p. 102860. (2023) Sung, S.-Y., et al.: Control of bacteria growth on ready-to-eat beef loaves by antimicrobial plastic packaging incorporated with garlic oil. Food Control. 39 , 214–221 (2014) Brandelli, A.: Nanobiotechnology strategies for delivery of antimicrobials in agriculture and food , in Nanotechnologies in food and agriculture , pp. 119–139. Springer (2015) Kim, M.J., et al.: Preparation of poly (vinyl alcohol)/silver-zeolite composite hydrogels by UV-irradiation. Fibers Polym. 15 (1), 101–107 (2014) Aldalbahi, A., et al.: Fabrication of biodegradable and antibacterial films of chitosan/polyvinylpyrrolidone containing Eucalyptus citriodora extracts. Int. J. Biol. Macromol. 266 , 131001 (2024) Zheng, H., et al.: Poly-(lactic acid) composite films comprising carvacrol and cellulose nanocrystal–zinc oxide with synergistic antibacterial effects. Int. J. Biol. Macromol. 266 , 130937 (2024) Kuplennik, N., et al.: Antimicrobial packaging based on linear low-density polyethylene compounded with potassium sorbate. LWT-Food Sci. Technol. 62 (1), 278–286 (2015) Lee, C.H., et al.: A coating for use as an antimicrobial and antioxidative packaging material incorporating nisin and α-tocopherol. J. Food Eng. 62 (4), 323–329 (2004) Devlieghere, F., et al.: The effectiveness of hexamethylenetetramine-incorporated plastic for the active packaging of foods. Packaging Technol. Sci. 13 (3), 117–121 (2000) Mousavian, D., et al.: Physicomechanical properties, release kinetics, and antimicrobial activity of activated low-density polyethylene and orientated polypropylene films by Thyme essential oil active component. J. Food Meas. Charact. 15 , 883–891 (2021) Ordon, M., et al.: Polyethylene films containing plant extracts in the polymer matrix as antibacterial and antiviral materials. Int. J. Mol. Sci. 22 (24), 13438 (2021) Moradi, E., et al.: Prolonging shelf life of chicken breast fillets by using plasma-improved chitosan/low density polyethylene bilayer film containing summer savory essential oil. Int. J. Biol. Macromol. 156 , 321–328 (2020) Chang, S., Mohammadi, A., Nafchi, Baghaie, H.: Development of an active packaging based on polyethylene containing linalool or thymol for mozzarella cheese, vol. 9, pp. 3732–3739. Food science & nutrition (2021). 7 Heras, M., et al.: Trends in chitosan-based films and coatings: A systematic review of the incorporated biopreservatives, biological properties, and nanotechnology applications in meat preservation. Food Packaging Shelf Life. 42 , 101259 (2024) Siddiqui, M.N., et al.: Development of bio-composites with enhanced antioxidant activity based on poly (lactic acid) with thymol, carvacrol, limonene, or cinnamaldehyde for active food packaging. Polymers. 13 (21), 3652 (2021) Motelica, L., et al.: Antibacterial biodegradable films based on alginate with silver nanoparticles and lemongrass essential oil–innovative packaging for cheese. Nanomaterials. 11 (9), 2377 (2021) Motelica, L., et al.: Innovative antimicrobial chitosan/ZnO/Ag NPs/citronella essential oil nanocomposite—Potential coating for grapes. Foods. 9 (12), 1801 (2020) Moazeni, M., Saharkhiz, M.J., Hosseini, A.A.: In vitro lethal effect of ajowan (Trachyspermum ammi L.) essential oil on hydatid cyst protoscoleces. Vet. Parasitol. 187 (1–2), 203–208 (2012) Omidpanah, S., et al.: Effects of Monoterpenes of Trachyspermum ammi on the Viability of Spermatogonia Stem Cells In Vitro. Plants (Basel). 9 (3), 343 (2020) Sivaram, S., et al.: The beneficial role of plant based thymol in food packaging application: A comprehensive review. Appl. Food Res. 2 (2), 100214 (2022) Adnan, M., et al.: Review on antibacterial activity of Himalayan medicinal plants traditionally used to treat pneumonia and tuberculosis. J. Pharm. Pharmacol. 71 (11), 1599–1625 (2019) El-Gebaly, A.S., et al.: Combination of nanoparticles (NPs) and essential oils (EOs) as promising alternatives to non-effective antibacterial, antifungal and antiviral agents: A review. Biocatal. Agric. Biotechnol., : p. 103067. (2024) Basavegowda, N., Baek, K.-H.: Synergistic antioxidant and antibacterial advantages of essential oils for food packaging applications. Biomolecules. 11 (9), 1267 (2021) Tian, B., et al.: Biopolymer food packaging films incorporated with essential oils. J. Agric. Food Chem. 71 (3), 1325–1347 (2023) Ebrahimzadeh, S., et al.: Incorporation of essential oils in edible seaweed-based films: A comprehensive review. Trends in Food Science & Technology (2023) Strasakova, M., et al.: Immobilization of caraway essential oil in a polypropylene matrix for antimicrobial modification of a polymeric surface. Polymers. 13 (6), 906 (2021) Hashim, R., et al.: Effects of incorporation of essential oil into film for fruit packaging application . in IOP Conference Series: Earth and Environmental Science . IOP Publishing. (2021) Min, T., et al.: Electrospun pullulan/PVA nanofibers integrated with thymol-loaded porphyrin metal-organic framework for antibacterial food packaging. Carbohydr. Polym. 270 , 118391 (2021) Daramola, O., et al.: Mechanical properties of high density polyethylene matrix composites reinforced with chitosan particles. Materials Today: Proceedings, 38: pp. 682–687. (2021) Verma, D.K., et al.: Synthesis, characterization and applications of chitosan based metallic nanoparticles: A review. J. Appl. Nat. Sci. 13 (2), 544–551 (2021) Mouhoub, A., et al.: Assessment of the antioxidant, antimicrobial and antibiofilm activities of essential oils for potential application of active chitosan films in food preservation. World J. Microbiol. Biotechnol. 38 (10), 179 (2022) Bi, J., et al.: Novel procyanidins-loaded chitosan-graft-polyvinyl alcohol film with sustained antibacterial activity for food packaging. Food Chem. 365 , 130534 (2021) Nostro, A., et al.: Study on carvacrol and cinnamaldehyde polymeric films: mechanical properties, release kinetics and antibacterial and antibiofilm activities. Appl. Microbiol. Biotechnol. 96 (4), 1029–1038 (2012) Solano, A.C.V., de Gante, C.: Two different processes to obtain antimicrobial packaging containing natural oils. Food and Bioprocess Technology, 5(6): pp. 2522–2528. (2012) Sung, S.-Y., et al.: Effects of Allium sativum essence oil as antimicrobial agent for food packaging plastic film. Innovative Food Sci. Emerg. Technol. 26 , 406–414 (2014) Wattananawinrat, K., Threepopnatkul, P., Kulsetthanchalee, C.: Morphological and thermal properties of LDPE/EVA blended films and development of antimicrobial activity in food packaging film. Energy Procedia. 56 , 1–9 (2014) Guarda, A., et al.: The antimicrobial activity of microencapsulated thymol and carvacrol. Int. J. Food Microbiol. 146 (2), 144–150 (2011) Esmaeili, A., Asgari, A.: vitro release and biological activities of Carum copticum essential oil (CEO) loaded chitosan nanoparticles. Int. J. Biol. Macromol. 81 , 283–290 (2015) Quiroz-Castillo, J.M., et al.: Preparation of extruded polyethylene/chitosan blends compatibilized with polyethylene-graft-maleic anhydride. Carbohydr. Polym. 101 , 1094–1100 (2014) Tonekaboni, H.B., Mehdikhani, S., Yazdani, H.: Fabricating chitosan/low-density polyethylene (CS-LDPE) films and its efficacy to prolong shelf life of rainbow trout fish. Food Bioscience. 57 , 103401 (2024) Basij, M., et al.: Insecticidal potential of Ajwain essential oil and its major components against Chilo suppressalis Walker. J. Plant Dis. Prot. 130 (4), 735–745 (2023) Shabani, M., et al.: Long-lasting adsorption of golden flower oil on polyvinyl alcohol/clinoptilolite (PVA/CP) xerogel particles. Appl. Clay Sci. 195 , 105699 (2020) Yang, Y., et al.: Chitosan nanocarriers containing essential oils as a green strategy to improve the functional properties of chitosan: A review. Int. J. Biol. Macromol. 236 , 123954 (2023) Dutta, S., et al.: Characterization, antifungal properties and in silico modelling perspectives of Trachyspermum ammi essential oil. Lwt. 131 , 109786 (2020) Van Krevelen, D.W., Te, K., Nijenhuis: Properties of polymers: their correlation with chemical structure; their numerical estimation and prediction from additive group contributions. Elsevier (2009) Reesha, K.V., et al.: Development and characterization of an LDPE/chitosan composite antimicrobial film for chilled fish storage. Int. J. Biol. Macromol. 79 , 934–942 (2015) Yarnpakdee, S., et al.: Extraction and physico–chemical characterization of chitosan from mantis shrimp (Oratosquilla nepa) shell and the development of bio-composite film with agarose. Polymers. 14 (19), 3983 (2022) Basu, A., et al.: Edible nano-bio-composite film cargo device for food packaging applications. Food Packaging Shelf Life. 11 , 98–105 (2017) Hadi, A.G., et al.: Extraction and characterization of Chitosan gained from oyster and fish shells and evaluation its application as antioxidant . in AIP Conference Proceedings. AIP Publishing LLC . (2022) Yusuf, Y., Arman, B., Cahyana, A.H.: Syntheses via phenolic oxidative coupling using crude peroxidase from Brassica juncea (L) Czern leaves and antioxidant evaluation of dimeric thymol. Mediterranean J. Chem. 3 (6), 1100–1110 (2015) Ahmad, A.L., Sumathi, S., Hameed, B.H.: Adsorption of residue oil from palm oil mill effluent using powder and flake chitosan: equilibrium and kinetic studies. Water Res. 39 (12), 2483–2494 (2005) Ma, Y., et al.: Preparation, characterization, in vitro release, and antibacterial activity of oregano essential oil chitosan nanoparticles. Foods. 11 (23), 3756 (2022) Han, X., et al.: Preparation, characterization and antibacterial activity of new ionized chitosan. Carbohydr. Polym. 290 , 119490 (2022) Zidan, T., Abdelhamid, A.E., Zaki, E.: N-Aminorhodanine modified chitosan hydrogel for antibacterial and copper ions removal from aqueous solutions. Int. J. Biol. Macromol. 158 , 32–42 (2020) Li, B., et al.: Synthesis, characterization, and antibacterial activity of cross-linked chitosan-glutaraldehyde. Mar. Drugs. 11 (5), 1534–1552 (2013) Esfandiari, N., et al.: Effect of the Processing Conditions on the Supercritical Extraction and Impregnation of Rosemary Essential Oil in Linear Low-Density Polyethylene Films. Processes. 11 (1), 11 (2023) Suppakul, P., et al.: Characterization of antimicrobial films containing basil extracts. Packaging Technol. Science: Int. J. 19 (5), 259–268 (2006) Shelly, M., et al.: Structural and free-hole volume characterization of high-density polyethylene-chitosan composites plasticized with palm oil. Polym. Eng. Sci. 61 (12), 3060–3068 (2021) Maamoun, A.A., Mahmoud, A.A.: Exploring the mechanical and bacterial prospects of flexible polyurethane foam with chitosan. Cellulose. 29 (11), 6323–6338 (2022) Pedroso, A.G., Rosa, D.S.: Mechanical, thermal and morphological characterization of recycled LDPE/corn starch blends. Carbohydr. Polym. 59 (1), 1–9 (2005) Dong, Z., et al.: Characterization and preservation performance of active polyethylene films containing rosemary and cinnamon essential oils for Pacific white shrimp packaging. Food Control. 92 , 37–46 (2018) Shakour, N., et al.: Investigating the properties of PLA-nanochitosan composite films containing Ziziphora Clinopodioides essential oil and their impacts on oxidative spoilage of Oncorhynchus mykiss fillets, vol. 9, pp. 1299–1311. Food Science & Nutrition (2021). 3 Shankar, S., Khodaei, D., Lacroix, M.: Effect of chitosan/essential oils/silver nanoparticles composite films packaging and gamma irradiation on shelf life of strawberries. Food Hydrocoll. 117 , 106750 (2021) Idris, A., et al.: A review on predictive tortuosity models for composite films in gas barrier applications. J. Coat. Technol. Res., : p. 1–18. (2022) Ramos, M., et al.: Characterization and antimicrobial activity studies of polypropylene films with carvacrol and thymol for active packaging. J. Food Eng. 109 (3), 513–519 (2012) Martínez-Tenorio, Y., et al.: Development of Antifungal Packaging From Low‐Density Polyethylene With Essential Oil of Oregano and Potassium Sorbate. Packaging Technology and Science (2024) Sharma, S., et al.: Essential oils as additives in active food packaging. Food Chem. 343 , 128403 (2021) Salmas, C.E., et al.: Development and evaluation of a novel-thymol@ natural-zeolite/low-density-polyethylene active packaging film: Applications for pork fillets preservation. Antioxidants. 12 (2), 523 (2023) Tan, W., et al.: Design, synthesis of novel chitosan derivatives bearing quaternary phosphonium salts and evaluation of antifungal activity. Int. J. Biol. Macromol. 102 , 704–711 (2017) Lim, S.H., Hudson, S.M.: Synthesis and antimicrobial activity of a water-soluble chitosan derivative with a fiber-reactive group. Carbohydr. Res. 339 (2), 313–319 (2004) Oladzadabbasabadi, N., et al.: Recent advances in extraction, modification, and application of chitosan in packaging industry. Carbohydr. Polym. 277 , 118876 (2022) Wang, L., et al.: Antibacterial food packaging capable of sustained and unidirectional release carvacrol/thymol nanoemulsions for pork preservation. Food Hydrocoll. 145 , 109169 (2023) Casalini, S., Giacinti, M., Baschetti: The use of essential oils in chitosan or cellulose-based materials for the production of active food packaging solutions: a review. J. Sci. Food. Agric. 103 (3), 1021–1041 (2023) Hajibonabi, A., et al.: Antimicrobial activity of nanoformulations of carvacrol and thymol: New trend and applications. OpenNano, : p. 100170. (2023) Ramos, M., et al.: Development of novel nano-biocomposite antioxidant films based on poly (lactic acid) and thymol for active packaging. Food Chem. 162 , 149–155 (2014) Alsakhawy, S.A., et al.: Comparative Phytochemical Composition and Antimicrobial Activity of Citrus Peel Essential Oils and Phenolic Compounds. Anti-Infective Agents, 21(4): pp. 57–68. For the TOC Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films Kasra Shiva 1 , 2 , Adel Soleimani 1 , 2 , Jalil Morshedian 1 , Farhid Farahmandghavi 2 , , and Fatemeh Shokrolahi 3 1 Department of Polymer Processing, Faculty of Processing, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran 2 Department of Novel Drug Delivery Systems, Faculty of Science, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran 3 Department of Biomaterials, Faculty of Science, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran (2023) Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4548087","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":315912217,"identity":"68982981-4e64-499b-853d-1ad9e201003d","order_by":0,"name":"Kasra Shiva","email":"","orcid":"","institution":"Iran Polymer and Petrochemical Institute","correspondingAuthor":false,"prefix":"","firstName":"Kasra","middleName":"","lastName":"Shiva","suffix":""},{"id":315912218,"identity":"7c454a70-0c48-41e5-90c4-fbe27986c474","order_by":1,"name":"Adel Soleimani","email":"","orcid":"","institution":"Iran Polymer and Petrochemical Institute","correspondingAuthor":false,"prefix":"","firstName":"Adel","middleName":"","lastName":"Soleimani","suffix":""},{"id":315912219,"identity":"8320ea2b-b707-4050-8ad0-4228a496748d","order_by":2,"name":"Jalil Morshedian","email":"","orcid":"","institution":"Iran Polymer and Petrochemical Institute","correspondingAuthor":false,"prefix":"","firstName":"Jalil","middleName":"","lastName":"Morshedian","suffix":""},{"id":315912220,"identity":"9d8b598e-72bf-4691-8c61-42003e9a0acc","order_by":3,"name":"Farhid Farahmandghavi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYBAC+wP8H4DUARDb8EECAwMPWDgBjxYDiBqwFmMDkrWYSRDlMKAWxs8VNXei+Wc3b6t4uOOODAP74QcMD/fg1mLPwH9Y8syxZ7kz7hwru5F45hkPA0+aAUPCM/wOk2xgO5zbcCPH7EZi22GgO3OAfjmAVwvzz4Z/h3PnA7UUgLXwvyGohU2yse1w7gagFgawFglCtjDzsFk29h3O3XgjrVgC5Bc2iWcGB/BqYe9hvtnw7XDuvBvJGz/+3HHHnp8/+eHDH3i0MDAjcxgbDjCwMUCjiTgA0jIKRsEoGAWjAB0AAHq9Ve7d7cuvAAAAAElFTkSuQmCC","orcid":"","institution":"Iran Polymer and Petrochemical Institute","correspondingAuthor":true,"prefix":"","firstName":"Farhid","middleName":"","lastName":"Farahmandghavi","suffix":""},{"id":315912221,"identity":"583bda4d-aeb6-41ae-ab65-19cb580057d1","order_by":4,"name":"Fatemeh Shokrolahi","email":"","orcid":"","institution":"Iran Polymer and Petrochemical Institute","correspondingAuthor":false,"prefix":"","firstName":"Fatemeh","middleName":"","lastName":"Shokrolahi","suffix":""}],"badges":[],"createdAt":"2024-06-07 21:05:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4548087/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4548087/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58993977,"identity":"61a4c305-cf01-449a-b2de-e1740c16c01d","added_by":"auto","created_at":"2024-06-25 05:42:57","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":38199,"visible":true,"origin":"","legend":"\u003cp\u003eAdsorption of various components of: A) essential oil on CS and B) normalized data.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/933a01050481ee36b6cd625e.jpg"},{"id":58992871,"identity":"66b127f8-3a3c-4c83-9a5c-45449cd3eb8f","added_by":"auto","created_at":"2024-06-25 05:26:57","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":74379,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of CS powder, AEO, PE (PE-0-0), and samples number PE-5-0 and PE-0-10.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/e215228b29edfa3699d8a540.jpg"},{"id":58993340,"identity":"672a10f6-6145-4d3f-862a-2cd790037e75","added_by":"auto","created_at":"2024-06-25 05:34:57","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":48025,"visible":true,"origin":"","legend":"\u003cp\u003eAmount and percentage composition of oil extracted from different samples: A) content of AEO extracted, B) content of different components of extracted AEO.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/4b866130449d2f30ab015ca8.jpg"},{"id":58993976,"identity":"62f50917-d236-4c06-b023-219f0fde2603","added_by":"auto","created_at":"2024-06-25 05:42:57","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":100464,"visible":true,"origin":"","legend":"\u003cp\u003eXRD pattern of the samples containing: a) both CS and AEO, b) AEO, c) CS and d Values for the first and second peaks of different samples with AEO and CS.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/55df1e980b4138ef73ded734.jpg"},{"id":58993343,"identity":"ce638d96-eddf-4a96-a1da-a3e4c3afe788","added_by":"auto","created_at":"2024-06-25 05:34:57","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":50272,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of CS and/or AEO on the OTR properties of different samples.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/3b87a580f025cc34f573d046.jpg"},{"id":58992876,"identity":"e923953f-639a-4d91-ad2f-40da96a2578e","added_by":"auto","created_at":"2024-06-25 05:26:57","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":111803,"visible":true,"origin":"","legend":"\u003cp\u003eA) TGA thermograms of the CS, AEO, PE-0-10 and PE-7.5-10. B) SEM micrographs of the cross section of the samples (B1) PE-0-10, (B2) PE-7.5-0 and (B3) PE-7.5-10.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/58cf15c67a4f2395c6fdb210.jpg"},{"id":58992872,"identity":"6317e961-e0cb-42af-8c09-0a11233ea667","added_by":"auto","created_at":"2024-06-25 05:26:57","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":88473,"visible":true,"origin":"","legend":"\u003cp\u003eInhibition zones of the samples incubated at 37 ˚C for 24 hr:s A) PE-5-0 and PE-7.5-0 against E. coli, B) PE-5-0 and PE-7.5-0 against S. aureus, C) PE-0-0, PE-0-10, PE-7.5-10 against E. coli, D) PE-0-0, PE-0-10, PE-7.5-10 against S. aureus.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/72c78df81f5a84da5626908a.jpg"},{"id":59219252,"identity":"acceccb2-e2ec-4eaf-9de6-5bf45319bb35","added_by":"auto","created_at":"2024-06-27 20:02:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1500070,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/86547337-7af9-4055-96b4-d0994616658b.pdf"},{"id":58993342,"identity":"5afccc5c-ea5e-412a-a6f5-27307ddf8a5a","added_by":"auto","created_at":"2024-06-25 05:34:57","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":267420,"visible":true,"origin":"","legend":"","description":"","filename":"FortheTOC.docx","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/1250ae5a12867d8f02218121.docx"},{"id":58992878,"identity":"e9ab3922-785f-4b36-9b5a-34a8a4891ee1","added_by":"auto","created_at":"2024-06-25 05:26:57","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":219595,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4548087/v1/25893f89245bd808cbb9c97e.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films","fulltext":[{"header":"1 Introduction","content":"\u003cp\u003eFood products mainly classified as perishable products, suffering from short shelf life. Furthermore, they are vulnerable to chemical reactions and bacterial contamination, and their quality may deteriorate during production, processing, transportation, and storage stages [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Along with the growing demand for healthy, less processed, and high-quality foods, these challenges are the driving force behind some dynamic changes in the food packaging industry [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong the polymers used in food packaging, polyolefins such as polyethylene (PE) and polypropylene (PP) are preferred for several reasons such as low cost, flexibility, chemical inertness, recyclability, good processability, non-toxicity, and biocompatibility. Since these polymers have very good sealing properties, they are also used as a bonding layer on aluminum foil when applying different polymers on the foil. Although LDPE is a good barrier against moisture, it is relatively permeable against oxygen and is considered a weak barrier against odors. Polyethylene also cannot limit the migration of microbes from the paper or mineral-coating pigments on the paper to the packaged food. These weak features make the use of this polymer challenging in food packaging applications and need to be improved. To improve the mechanical properties of LDPE, it is blended with linear low-density polyethylene (LLDPE), so it can better withstand the strain of transportation [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePassive traditional food packaging techniques, involves the use of a covering material, which only act as a barrier to postpone harmful environmental effects, and cannot guarantee food protection and quality [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. As a result, a switch from the standard conception of packaging to minimize the interaction between food and packaging material to a novel view emphasizing the favorable effects of some food/package interactions seems inevitable. A most recent alternative with promising potentials in this field is active packaging, as a system with ability of changing conditions of the wrapped products, which can enhance the preservation of properties, provides better safety, prolongs shelf-life, and protect the quality of foods [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Among different sorts of active packaging, the antibacterial types are the most innovative concepts in the food industry. These systems intermingle the protective features of antibacterial agents with preservative characteristics for foods[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In direct use of antibacterial agents in foods have a reasonably large antibacterial effect, due to quick diffusion of antibacterial component into the bulk. however, adverse effects of antibacterial agents such as food denaturation and off-flavoring may also occur. Therefore, the use of antibacterial agents within the package film matrix could be useful for a gradual and steady liberation over a long time. thus, the antibacterial effect could have been sustained over a long period of time[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAnother solution to achieve the desired antibacterial activity is provided through indirect contact between food and antibacterial agent, by direct use of antibacterial compounds in the film package [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Using antibacterial agents in polyethylene food packaging systems have already been evaluated such as Thymol, Potassium sorbate, Nisin, Hexamethylenetetramine, organic acid and chitosan/essential oil [\u003cspan additionalcitationids=\"CR16 CR17 CR18 CR19 CR20\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition, among indirect methods, using oxidizing ions such as copper or silver ions as antibacterial agents in food packaging systems, have already been evaluated. But they should be consumed optimally because of their potential for toxicity. Meanwhile, a tremendous rise in bacterial resistance to antibiotics has increased the global trend towards using natural additives - such as essential oils (EOs) \u0026ndash; in the food packaging industry. Natural extracts such as EOs and their constituents possess the GRAS (Generally recognized as safe) status by the US Food and Drug Administration (FDA) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. They also have been classified by the European Decision 2002/113/EC (Commission Decision 2002/113/EC) as flavorings [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In this sense, packaging producers and consumers consider the impregnation of polymeric plastic films by these agents as an attractive method to avoid bacterial food contaminations.\u003c/p\u003e \u003cp\u003eGenerally, there are different natural chemical compounds capable of antibacterial activity [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e], including terpenoids and sesquiterpenes with various aliphatic hydrocarbons, aldehydes, acids, alcohols. Thymol is the main constituent of Trachyspermum ammi, also known as Ajwain, and can be extracted between 35 to 60% from the plant [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The non-thymol fraction includes para-cymene, Gamma-terpinene, Alpha-pinene, carvacrol, and other minor constituents [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Thymol is a predominant monoterpene phenolic compound which has been used as a food preservative for many years. With a wide range of antibacterial activity, thymol is capable of a high potential for perishable foods' safety and prolongs shelf life [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Thymol and carvacrol, which are isomers, are hydrophobic compounds that can easily dissolve in the hydrophobic domain of the bacterial cytoplasmic membrane and the lipid acyl chains, leading to a noticeable effect on the membrane and its functional and structural properties. although many studies have so far demonstrated the antibacterial activity of EOs and their active components against a wide range of pathogenic bacteria [\u003cspan additionalcitationids=\"CR30 CR31\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], only a few articles have focused on the use of EOs as additives in polymeric plastic films used for food packaging [\u003cspan additionalcitationids=\"CR34\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMin et al. used thymol as antibacterial agent and introduced a composite of THY@PCN/PUL/PVA nanofibers and claimed that the composite has the ability of sustained release of thymol as dual-antibacterial activity to prolonged the shelf life of fruits. Although it is not clear whether the use of Pullulan in packaging is economical or not [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong active biopolymers, chitosan (CS) is of great interest in the food industry due to its unique properties such as antibacterial activity, biodegradability, biocompatibility and non-toxicity. CS, the linear and partly acetylated (1\u0026ndash;4)-2-amino-2-deoxy-\u0026lt;beta\u0026gt;-d-glusan, can be easily derived from chitin, the second most abundant natural polymer, found in crab, shrimp, lobster, coral, jellyfish, mushroom, and fungi [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. It had been proven that CS is capable of absorbing oils and hydrophobic compounds on its surface [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. Bi, J., et al. claimed that CS-graft-PVA film had a potential ability to be applied as a carrier to bind quantities of procyanidins to prepare an active food packaging, that the procyanidin encapsulation efficiency is over 95% and long-term release sustainability [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe lack of interest in this field may be because essential oils and their compounds are heat and shear-sensitive components, so, can quickly decompose or evaporate under high processing temperature and pressure. To overcome this problem, some researchers have used innovative methods. Nestro et al. fabricated active films based on ethylene-vinyl acetate (EVA) incorporated with 3.5 and 7% carvacrol or cinnamaldehyde by minimizing the mixing time and placing the material in the liquid nitrogen bath immediately after mixing to prevent any further evaporation of the antibacterial additive [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Solano et al. produced LDPE films with 1 and 4% Origanum vulgare and Thymus vulgaris using a single screw extruder. From the feed zone to die, the temperature profile was increased gradually to preserve the antibacterial additive from evaporation[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. A mixture of LDPE and EVA was chosen to enhance the solubility and to ensure partial adhering of the EOs in the polymer matrix. The relatively higher retention of EOs in the film with is capable by higher concentration and lower polarity [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Guarda et al. coated corona-treated bi-axially oriented PP films with microcapsules containing thymol and carvacrol as natural antibacterial agents [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEsmaili and Asgari presented a method in which Carum copticum essential oil (CEO) encapsulated in CS nanoparticles. In the method, encapsulation of CEO in the particles was performed by an emulsion-ionic gelation with creating of crosslinking using pantasodium tripolyphosphate (TPP) and sodium hexametaphosphte (HMP), separately [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of this research is to use Ajwain essential oil (AEO) in polyethylene-based food packaging films as an antibacterial agent. As explained AEO is sensitive to the environmental conditions and evaporates at the elevated temperature required to prepare polyethylene films, so, the main challenge of this research is to solve this problem. We decided to use the surface adsorption of AEO on chitosan particles to preserve it in the harsh conditions and high temperature of the process, which is a very efficient and simple method. To the best of our knowledge no research yet has been accomplished the adsorption of AEO molecules on CS particles in antibacterial food packaging systems. To improve the distribution of CS chains in the LDPE-LLDPE matrix, PE-graft-maleic anhydride (PE\u003csub\u003ema\u003c/sub\u003e) was used as a compatibilizer [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e]. The innovation of this research is the use of CS particles (2.5-7% w/w) as an active carrier for Ajwain essential oil (AEO) to minimize its evaporation during the melt processing and enhance the thermal stability of the absorbed active oil.\u003c/p\u003e"},{"header":"2 Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Materials\u003c/h2\u003e \u003cp\u003eThe polymers used in this study were LDPE and LLDPE purchased from Amir Kabir Petrochemical Industry, Iran, with 209AA and 2420F, respectively, and PE\u003csub\u003ema\u003c/sub\u003e was from Karangin, Iran. The antibacterial agent was AEO supplied from Barij Essence Co., Iran. Powdered CS was obtained from Bio Basic, Canada, CAS 9012-76-4, high MW, with at least deacetylation of 90% and dried at 100\u0026deg;C for 5 hours before use. Ethanol, decane, and acetone were purchased from Merck, Germany, and utilized as received.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Methods\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1 Pellet preparation\u003c/h2\u003e \u003cp\u003e960 grams (g) of LDPE and LLDPE (with a mass ratio of 70/30) was pre-mixed with 40 g of PE\u003csub\u003ema\u003c/sub\u003e and fed to a twin-screw extruder (Brabender, ZSK-25, Germany) with an L/D ratio screw of 40 and a screw speed of 250 rpm with a feeding rate of 2 kg/hr. The temperature was 215\u0026deg;C (all zones). By passing through the extruder and because of shear and pressure forces, all materials were thoroughly mixed. As a result of passing through a basin of cold water, the molten material was left in string form, forming in granule shape using a pelletizer machine.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2 AEO adsorption on CS particles\u003c/h2\u003e \u003cp\u003eFirst, CS particles with a particle size of less than 108 microns were placed in an oven at 70\u0026deg;C for 5 hours to dry. 100 \u0026micro;L of AEO, dissolved in 3.5 mL of acetone, in 10 mL test tubes. Then 0.5 g CS was gradually added to the tubes. The tubes were sealed and located in a water bath and equilibrated at ambient temperature. Solid particles were separated from the mixture after 30, 60, 90, 180, 360, and 720 min by centrifugation at 5000 rpm (Sigma 2K15C refrigerated centrifuge, Sigma, England) for 5 minutes. The amount of AEO absorbed on CS particles was characterized and quantified according to the following method. Decane solution (2 mL, 120 ppm in acetone) as internal standard was added to 2 mL of the solution, and the mixture passed through a syringe-head Teflon filter (Spartan 0.2 \u0026micro;m, Whatman, England) and injected into gas chromatography-mass spectroscopy (GC- Mass) equipment. The concentration of each of the components was determined according to Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\frac{{AUCIS}}{{AUCAEO\u0026#039;s{\\text{ }}Component}}=\\frac{{CIS}}{{CAEO\u0026#039;s{\\text{ }}Component}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eAUC\u003c/em\u003e \u003csub\u003e \u003cem\u003eIS\u003c/em\u003e \u003c/sub\u003e and \u003cem\u003eAUC\u003c/em\u003e\u003csub\u003e\u003cem\u003eEO\u0026rsquo;s\u003c/em\u003e\u003c/sub\u003e components are the signals area for decane solution (internal standard) and any specific component of the AEO, respectively. \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003eIS\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003eAEO\u0026rsquo;s\u003c/em\u003e\u003c/sub\u003e components represent the concentration of decane and the specific AEO\u0026rsquo;s component, respectively. The AEO absorbed amount on CS (\u003cem\u003en\u003c/em\u003e\u003csub\u003e\u003cem\u003eabsorbed\u003c/em\u003e\u003c/sub\u003e) was calculated by subtracting amount of AEO\u0026rsquo;s components in the supernatant (\u003cem\u003en\u003c/em\u003e\u003csub\u003e\u003cem\u003esupernatant\u003c/em\u003e\u003c/sub\u003e) from the initial AEO\u0026rsquo;s components (\u003cem\u003en\u003c/em\u003e\u003csub\u003e\u003cem\u003eblank\u003c/em\u003e\u003c/sub\u003e) in control sample (Eq.\u0026nbsp;(\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)).\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$n{\\text{adsorbed}}=n{\\text{blank}}-n{\\text{supernatant}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3 AEO/CS contact time\u003c/h2\u003e \u003cp\u003eThree samples containing 3 gr of CS and different amounts of AEO (2, 3 and 4 gr), were prepared in three separate beakers. CS particles followed by a contact time of 6 h at room temperature to complete the process of adsorption. The optimum contact time was determined using GC-Mass analysis. The mixture was later mixed with PE granules in an internal mixer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4 Film preparation\u003c/h2\u003e \u003cp\u003ePrepared granules were blended with different amounts of AEO and/or CS and AEO-absorbed CS particles by melt mixing in a batch mixer (Brabender w-50, Germany). Initially, the granules were fed to the mixer at a temperature of 115\u0026deg;C and a rotor speed of 100 rpm. After melting for 3 min, the rotational speed decreased to 60 rpm (to protect the active oil compounds from oxidation and evaporation), and AEO, CS, or a mixture of both of them were added and to minimize the evaporation, the blending process continued for no longer than 2 min. The resulting melt mixed blends were hot-pressed for 1 min at 140\u0026deg;C under 150 bars using an electrically heated hydraulic press to obtain approximately 120 \u0026micro;m thick films. The antibacterial films developed with this method were immediately wrapped in aluminum foil and stored in plastic bags at 0\u0026ndash;3\u0026deg;C for up to 1 week before their final use. Different formulations prepared in this research are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The samples were named Polyethylene-A-B where A and B present the percentages of the chitosan and essential oil, respectively. It should be noted that all samples contain 4%w/w of PE\u003csub\u003ema\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eFormulations of the prepared samples\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCS % (w/w)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAEO % (w/w)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePE\u003csub\u003ema\u003c/sub\u003e % (w/w)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLDPE\u0026thinsp;+\u0026thinsp;LLDPE % (w/w)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e96\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-2.5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e93.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e88.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e88.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e86\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-2.5-10*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e93.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-5-10*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e91\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-5*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-7.5*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-10*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*The samples prepared by mixing the LLDPE, LDPE and PE\u003csub\u003ema\u003c/sub\u003e with AEO-absorbed CS particles\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Characterization\u003c/h2\u003e \u003cp\u003eStructural characterization of the samples was done by FTIR. AEO and CS were separately mixed with KBr powder and then pressed into pellets for FTIR spectroscopy. Films with different formulations were cut into 2\u003csub\u003e*\u003c/sub\u003e2 cm\u003csup\u003e2\u003c/sup\u003e samples and were fixed to a sample holder on a Bruker, Equinox 55, Germany. We recorded 16 scans at a resolution of 4 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for each spectrum. Measurements were recorded from wave number 400\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe amount of AEO in the samples was determined by GC-Mass. Five grams of the film samples were cut and extracted for about 24 h by Soxhlet extraction using 200 mL ethanol. One \u0026micro;l aliquot of the extracted solution was characterized by Agilent 6890, USA (GC), and Agilent 5973, USA (MS) equipped with a fused silica capillary column (HP-5 MS). Primary column temperature was 50\u0026deg;C and heating rate of 5\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e applied until 220\u0026deg;C, then kept this temperature for 4 min before sampling; split ratio, 1:100; carrier gas, helium and a decane solution (2 mL, 120 ppm in acetone) was used as an internal standard.\u003c/p\u003e \u003cp\u003eAlso, AEO was analyzed by GC-MS technique. 10 \u0026micro;L of AEO was diluted by 2 mL ethanol, and the resulting solution (0.5\u0026micro;L) was injected for the GC-MS test while the condition mentioned above was applied.\u003c/p\u003e \u003cp\u003eAdsorption of AEO constituents on CS particles after different contact times (1, 1.5, 3, 6, 12 hrs.) was also determined by GC-Mass analysis. By absorbing AEO constituents on CS particles, their concentration decreased after specific intervals. The quantification of GC-Mass test results is based on comparing the area below the peak related to decane with the peaks of AEO components. Normalized data was achieved by dividing the absorbed amount for each constituent by its percentage.\u003c/p\u003e \u003cp\u003eThe crystal structure analysis of the samples and CS powder was performed using XRD. X-ray diffraction (XRD) patterns were obtained by using a SIEMENS, D5000 (Germany) with a detector operating (voltage\u0026thinsp;=\u0026thinsp;40 kV, current\u0026thinsp;=\u0026thinsp;40 mA) with Cu kα radiation. The scanning speed was 1.2 \u0026deg;/min, and the scanning scope of 2Ɵ was 5\u0026ndash;80\u0026deg;.\u003c/p\u003e \u003cp\u003eTo study the effect of AEO and/or CS on polymer mechanical properties, tensile strength and elongation at break of the samples were evaluated. Samples were cut lengthwise and cross direction 115*19 mm according to the ASTM D-638 method. The strips were mounted and clamped with pneumatic grips on a universal testing machine SANTAM, STM-20, with an initial grip distance of 30 mm. The rate of grip separation was 50 mm/min with a load cell of 1000 N and measurements were performed on 5 replicates for each sample.\u003c/p\u003e \u003cp\u003eThe gas barrier properties were represented by the oxygen transmission rate (OTR). Measurements were carried out by using a GDP-C gas permeability tester (Coesfeld Meterialtest, Germany) according to ASTM D 1434. Each film sample was 14 cm in diameter, and measurements were carried out at 23\u0026deg;C and 50% RH.\u003c/p\u003e \u003cp\u003eThe thermal stability of the films was monitored using a thermogravimetric analyzer (TOLEDO, METTLER, Switzerland). By recording thermogravimetric data, the film samples' mass-loss curves vs. temperature were obtained. All the experiments were performed at a heating rate of 10\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and inert nitrogen atmosphere in the temperature range 25\u0026ndash;600\u0026deg;C.\u003c/p\u003e \u003cp\u003eSEM was used to study the morphology of fracture surfaces. The cross-section morphology of the samples was investigated by TESCAN model VEGA, the Czech Republic scanning electronic microscope, using an accelerating voltage of 5\u0026ndash;30 kV. The samples were immersed in liquid nitrogen for 1 min and fractured to analyze the cross-section. The samples were sputter-coated with the gold layer before analyzing to avoid electrostatic charging under the electron beam and increase electrical conductivity. The antibacterial activity of polymeric films containing AEO and/or CS was evaluated quantitatively against two food spoilage bacteria, including Gram-negative bacteria, Escherichia coli (E.coli) and Gram-positive bacteria, Staphylococcus aureus (S.aureus). Virgin film without AEO and CS was included as controls. The bacterial strains selected here representing typical spoilage microorganisms widely occurring in various types of food products.\u003c/p\u003e \u003cp\u003eThe antibacterial activity of active films was determined using the agar disc diffusion assay. Polymeric films were cut into disc whit 1 cm diameter and placed in the middle of the Petridishes containing nutrient agar purchased from Merk, Germany. From each inoculum (10\u003csup\u003e6\u003c/sup\u003e CFU/mL), 0.1 mL was spread onto the plate medium. Then, the Petri dishes were placed in an incubation chamber at the appropriate conditions (37\u0026deg;C for 24 h). The antibacterial activity of each sample was determined by observing the clear zone of the targeted microorganisms around the active films. The diameter of the zone was measured by a digital micrometer and recorded as the ratio of the zone of inhibition area to the sample area. Mueller Hinton Agar medium was used for determining antibacterial activity. The test was carried out in duplicate for each formulation. The inhibitory activity against E coli and S. aureus was evaluated by measuring the diameter of the transparent inhibition zone, and the antibacterial effect was evaluated by comparing inhibition zone diameters The average and standard deviation of two measurements were calculated.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Statistical Analysis\u003c/h2\u003e \u003cp\u003eData points were presented as the mean of the measured values. The data were exposed to an analysis of variance (ANOVA) at the level of significance at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 using the Originlab 2022 software package. Statistical procedure was resolved by means of confidence intervals using Tukey\u0026rsquo;s test.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results and discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Characterization of essential oil\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e3.1.1 GC-Mass Analysis\u003c/h2\u003e \u003cp\u003eGC-Mass results of AEO are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e (GC-Mass chromatograms (\u003cb\u003eFigure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e\u003c/b\u003e) is in the supporting information). According to the results, different constituents were identified using their retention time indices and mass spectra fragmentation from the Nist and Wiley library, examining the fragmentation profiles and comparing them with those described in the literature. Thymol (47.34%w/w), ρ-cymene (28.59%w/w), and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene (16.24%w/w) were the main constituents which more than 92%w/w of the AEO components was related to them, followed by carvacrol (1.27%). Basij \u003cem\u003eet al.\u003c/em\u003e also described thymol, ρ-cymene, and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene as the major compounds of AEO with 90\u0026ndash;97% of the total components [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e]. It is worth noting that ρ-cymene and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene are the main precursors for thymol and carvacrol biosynthesize hence, high levels of these two components result in the high thymol percentage in AEO.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGC-Mass results of AEO.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRT\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eArea (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLibrary/ID\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAEO component\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eStructure\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e10.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e28.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBenzene,1-methyl-2-(1-methyl)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eρ-cymene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e11.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1,4-cyclohexadiene, 1-methyl-4-(1-methylethyl)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e47.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThymol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ethymol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3-Methyl-4-isopropylphenol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ecarvacrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 AEO adsorption on CS\u003c/h2\u003e \u003cp\u003eThe dependence of AEO physical adsorption on CS with time[\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e] was used to find the optimum contact time between AEO and CS particles. GC-Mass chromatograms of samples with different contact times are presented in Supporting information (\u003cb\u003eFigures S2 \u0026ndash; S4\u003c/b\u003e). It is obvious that, there are significant differences between peaks and their intensity in different samples. Since there are three major constituents in the AEO (thymol, ρ-cymene, and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene), the variation in the adsorption of these components was evaluated (based on the literature [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]). Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA shows the adsorption of different constituents on CS at different time intervals. Since, absorbed AEO amounts directly influence the corresponding adsorption of each constituent, the graph was normalized (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB). So, adsorption is a selective process, and CS particles' tendency for thymol uptake is more evident compared to ρ-cymene and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene. Theoretical results[\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e] (Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) and As it is clear from Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, (solubility parameters were obtained according to the Van Krevelen \u003cem\u003eet al.\u003c/em\u003e book \u003csup\u003e53\u003c/sup\u003e) the total dissolution variable (δTotal) for the 3 dominant components of Ajwan essential oil varies from 32.39 for thymol to 10.32 for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\gamma }\\)\u003c/span\u003e\u003c/span\u003e -terpinene. The partial dissolution variable of dispersion (δD) has the largest contribution to the total dissolution variable, which indicates the lipophilic nature of essential oil components. The lowest dispersion partial dissolution variable is 32.08 for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\gamma }-\\text{t}\\text{e}\\text{r}\\text{p}\\text{i}\\text{n}\\text{e}\\text{n}\\text{e}\\)\u003c/span\u003e\u003c/span\u003e and the highest is 36.59 for thymol. On the other hand, polar (δP) and hydrogen (δH) partial dissolution variables have the least contribution to the overall dissolution variable. The lowest partial polar dissolution variable for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\gamma }-\\text{t}\\text{e}\\text{r}\\text{p}\\text{i}\\text{n}\\text{e}\\text{n}\\text{e}\\)\u003c/span\u003e\u003c/span\u003e is 0.92 and the highest is 2.39 for thymol. The partial hydrogen dissolution variable for ρ-cymene and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\gamma }-\\text{t}\\text{e}\\text{r}\\text{p}\\text{i}\\text{n}\\text{e}\\text{n}\\text{e}\\)\u003c/span\u003e\u003c/span\u003e is zero, and the highest is 14.20 for thymol.\u003c/p\u003e \u003cp\u003eAs can be seen in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the value of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {{\\delta }}_{\\text{i}.\\text{j}}\\)\u003c/span\u003e\u003c/span\u003e for the three constituent components of AEO essential oil is close to each other, and it can be expected that the affinity of these three components to be absorbed on chitosan is close to each other and similar adsorption is expected for these components on chitosan. According to the theory, three components should be absorbed almost equally, but due to the higher molecular weight, density and boiling point of Thymol compared to the other components, the thymol is more absorbed.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e) further anticipated a close adsorption amount for different constituents.\u003c/p\u003e \u003cp\u003eThe dissolution between soluble component i and solvent j (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {\\delta }_{i.j}\\)\u003c/span\u003e\u003c/span\u003e) is calculated from Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e):\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\varDelta {\\delta }_{i.j}=\\sqrt{4{\\left({\\delta }_{D}^{i}- {\\delta }_{D}^{j}\\right)}^{2}+{\\left({\\delta }_{P}^{i}- {\\delta }_{P}^{j}\\right)}^{2}+{\\left({\\delta }_{H}^{i}- {\\delta }_{H}^{j}\\right)}^{2}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn which, dispersion forces (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{D}\\)\u003c/span\u003e\u003c/span\u003e), intermolecular dipole forces (dipole interactions) (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{P}\\)\u003c/span\u003e\u003c/span\u003e) and energy of hydrogen bonds between molecules (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{H}\\)\u003c/span\u003e\u003c/span\u003e) should be calculated.\u003c/p\u003e \u003cp\u003eThe smaller \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {\\delta }_{i.j}\\)\u003c/span\u003e\u003c/span\u003eis, the greater the affinity between solvent and solute. To estimate \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{D}\\)\u003c/span\u003e\u003c/span\u003e, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{P}\\)\u003c/span\u003e\u003c/span\u003e and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{H}\\)\u003c/span\u003e\u003c/span\u003e, a method based on the structural participation of functional groups was used. In this way, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{D}\\)\u003c/span\u003e\u003c/span\u003e is calculated from the Eq.\u0026nbsp;(\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e):\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$${\\delta }_{D}= \\frac{\\sum {F}_{D}}{{V}_{m}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{D}\\)\u003c/span\u003e\u003c/span\u003eis the dispersion component of molar absorption constant. If the substance has only one polar group, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{P}\\)\u003c/span\u003e\u003c/span\u003ecan be calculated from the relation \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{P}= \\frac{{F}_{P}}{{V}_{m}}\\)\u003c/span\u003e\u003c/span\u003e, but for more than one polar group, it is necessary to calculate the interactions of polar groups with the help of the Eq.\u0026nbsp;(\u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e5\u003c/span\u003e):\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$${\\delta }_{P}= \\frac{\\sqrt{\\sum {F}_{P}^{2}}}{{V}_{m}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere, \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{P}\\)\u003c/span\u003e\u003c/span\u003e is the polar component of molar adsorption constant. Although the \u003cem\u003eF\u003c/em\u003e method is not directly applicable in the calculation of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{H}\\)\u003c/span\u003e\u003c/span\u003e, but Birbauer and Hansen assumed that the hydrogen bonds are additive, which led to the Eq.\u0026nbsp;(\u003cspan refid=\"Equ6\" class=\"InternalRef\"\u003e6\u003c/span\u003e):\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ6\" name=\"EquationSource\"\u003e\n$${\\delta }_{H}= \\sqrt{\\frac{\\sum {E}_{H}}{{V}_{m}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({E}_{H}\\)\u003c/span\u003e\u003c/span\u003eis the hydrogen bond energy for each structural group (\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({F}_{H}{V}_{im}\\)\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAs it is clear from Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, (solubility parameters were obtained according to the Van Krevelen \u003cem\u003eet al.\u003c/em\u003e book [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]) the total dissolution variable (δ\u003csub\u003eTotal\u003c/sub\u003e) for the 3 dominant components of Ajwan essential oil varies from 32.39 for thymol to 10.32 for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e -terpinene. The partial dissolution variable of dispersion (δ\u003csub\u003eD\u003c/sub\u003e) has the largest contribution to the total dissolution variable, which indicates the lipophilic nature of essential oil components. The lowest dispersion partial dissolution variable is 32.08 for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene and the highest is 36.59 for thymol. On the other hand, polar (δ\u003csub\u003eP\u003c/sub\u003e) and hydrogen (δ\u003csub\u003eH\u003c/sub\u003e) partial dissolution variables have the least contribution to the overall dissolution variable. The lowest partial polar dissolution variable for \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene is 0.92 and the highest is 2.39 for thymol. The partial hydrogen dissolution variable for ρ-cymene and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene is zero, and the highest is 14.20 for thymol.\u003c/p\u003e \u003cp\u003eAs can be seen in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the value of \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {\\delta }_{i.j}\\)\u003c/span\u003e\u003c/span\u003e for the three constituent components of AEO essential oil is close to each other, and it can be expected that the affinity of these three components to be absorbed on chitosan is close to each other and similar adsorption is expected for these components on chitosan. According to the theory, three components should be absorbed almost equally, but due to the higher molecular weight, density and boiling point of Thymol compared to the other components, the thymol is more absorbed.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMolar volume and partial solubility variables of essential oils of Ajwain and chitosan.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ecomponent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMolar volume\u003c/p\u003e \u003cp\u003e(cc/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{H}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left({MPa}^{1/2}\\right)\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{P}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left({MPa}^{1/2}\\right)\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{D}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left({MPa}^{1/2}\\right)\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\delta }_{Total}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\left({MPa}^{1/2}\\right)\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {\\delta }_{i.j}\\)\u003c/span\u003e\u003c/span\u003e with chitosan\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ethymol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e99.211\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e36.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e39.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42.93\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eρ-cymene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e107.877\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e32.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e32.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42.15\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e-terpinene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e119.999\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e32.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e32.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e40.83\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e302.080\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e15.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e29.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e testify that 6 h is the optimum time for AEO uptake by CS particles. It is worth mentioning that the physical interaction between CS particles and AEO retains the AEO molecules in the film during the processing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Characterization of the LDPE/LLDPE/CS/AEO loaded films\u003c/h2\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.3.1 FTIR analysis\u003c/h2\u003e \u003cp\u003eFTIR spectra of the individual components are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The spectrum of CS powder displays an accentuated absorption peak at 3444cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, showing the stretching vibration of \u0026ndash;(NH\u003csub\u003e2\u003c/sub\u003e) and \u0026ndash;(OH) as well as inter and intramolecular hydrogen bonding. The peak at 2861cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to \u0026ndash;(CH) asymmetric stretching vibration. The peak around 1650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponds to the carbonyl group, which shows the acetylated amino groups of chitin, indicating an incomplete deacetylation process of the CS [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e]. Peaks at 1656 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1596 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for carbonyl stretching vibration (amide-1), N-H stretching vibration (amide-2), respectively correspond to the amide linkages [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. The peaks at 1382 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1035 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are assigned to the saccharide and \u0026ndash;(C-O-C)- stretching vibration of glucosamine ring, respectively [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe neat polyethylene spectrum shows a hydrocarbon stretching peak around 2848-2913cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The peaks of 1467 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 717 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to the methylene scissoring and methylene rocking vibrations, respectively [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn the case of PE-5-0 spectrum, widening in 3700 and 3000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e due to CS addition is shown. The depicted peak at 1035 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is attributed to the vibration of \u0026ndash;(C-O-C)- groups in CS.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs AEO is a mixture of different components, FTIR can only detect different functional groups but not the constituents. The spectrum exhibits a peak at 3421cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e attributed to hydroxyl \u0026ndash;(OH) stretching vibration groups of phenolic compounds[\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. The absorption peaks at 2960-2867cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are assigned to the symmetric and asymmetric stretching (C-H) groups. The spectrum from 1400\u0026ndash;1500 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e shows the C-H sp\u003csup\u003e3\u003c/sup\u003e bending and stretching vibration of the aromatic ring. The peak around 1149 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicates meta-substitution for thymol. The peaks 1087 and 1289 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e attributed to the thymol component. The absorption peaks at 1056 and 1513cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are assigned to the para-substitution and C-H(CH\u003csub\u003e3\u003c/sub\u003e) waging of p-cymene. The peaks at 860, 1170, and 1250 attribute to carvacrol\u0026mdash;the peak at 1619 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e assigned to the aromatic ring [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e]. The peak at 805\u0026ndash;810 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is because of plane alkene C-H stretching [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePE-0-10 spectrum exhibits the characteristic bands of the polymer matrix and those of AEO simultaneously. The peaks representing the polymeric matrix could be seen at 2884\u0026ndash;2913, 1467, and 717 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Since the observed peaks in the FTIR spectrum is the sum of the absorption of polymer matrix and AEO bonds, widening between 2848\u0026ndash;2960 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is due to overlapping bands assigned to stretching frequency of \u0026ndash;(CH\u003csub\u003e3\u003c/sub\u003e) groups in AEO and polymer matrix. The characteristic peaks of AEO could be observed at 3421, 1289, 1149, and 1056 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e which was already explained.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.3.2 AEO Loaded films\u003c/h2\u003e \u003cp\u003eAfter optimizing the time required to absorb AEO on CS, AEO-absorbed CS particles were mixed with PE, and the films were prepared as mentioned before, then the extraction of the remaining of AEO from the films was done. The extracted solution was injected into the GC-Mass after addition of decane. The results of the experiment are given in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e as examples for two samples. The relevant chromatograms can be seen in Supporting information \u003cb\u003e(Figures S5-S6).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eGas chromatographic results of the PE-0-10 and PE-7.5-10 samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRetention time (min)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eChemical composition\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePercentage of the components (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eComponent weight per gram of film (mg/g)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003ePE-7.5-7.5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9.297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDecane (standard)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.502\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.043\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eρ-cymene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8.461\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.792\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e -terpinene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.613\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.545\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17.884\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ethymol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e83.359\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.792\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ecarvacrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.393\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.514\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e\u003cb\u003ePE-7.5-10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9.291\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDecane (standard)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.597\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10.037\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eρ-cymene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.842\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.892\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.080\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\gamma\\)\u003c/span\u003e\u003c/span\u003e -terpinene\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.826\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.406\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17.890\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ethymol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e78.498\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e42.591\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ecarvacrol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.449\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.677\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows different component amounts of AEO loaded in the samples. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA indicates extracted AEO in milligrams per gram of each film. As seen in the Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the AEO loading amount is significantly higher in CS containing films and by increasing the amount of CS, the percentage of absorbed AEO increases. It could be attributed to the tendency of CS to the oil adsorption and high aspect ratio of the powder [\u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e, \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe results shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, reveal two important points. First, the presence of CS reduces oil evaporation during the film formation. Second, among the components of AEO, thymol evaporates less than para-cymene and gamma-terpinene, indicating that CS absorb more thymol in comparison with the others. This test provided a similar result regarding AEO adsorption on CS. In addition, the molecular weight of thymol is higher than para-cymene and gamma-terpinene. The simultaneous effect of these two factors causes the high thymol content in the samples. It should be noted that the above reasons are also valid for carvacrol, but owing to low percentage of this component, it does not have much effect on the final properties of the film.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eConsidering that the samples containing 2.5 and 5% chitosan and 10% AEO (samples PE-2.5-10 and PE-5-10 in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) have absorbed a smaller amount of essential oil than the PE-7.5-10 sample, so other tests were continued on the sample containing 7.5%w/w chitosan.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.3.3 XRD analysis\u003c/h2\u003e \u003cp\u003eX-ray diffraction testing is commonly used to identify the crystalline or amorphous structure of materials based on their diffraction patterns and provide documentary evidence to describe polymorphic structures.\u003c/p\u003e \u003cp\u003eThe XRD pattern of the polymer, CS, and the composite samples are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. As can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, the XRD pattern of CS illustrates two peaks at 2θ of 10.63\u0026deg; and 19.8\u0026deg;, were assigned to the (110) and (200) lattice planes, typical fingerprints of semi-crystalline CS which is in agreement with the results presented in the literature [\u003cspan additionalcitationids=\"CR62\" citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e]. The high degree of crystallinity of CS is attributed to a large quantity of hydroxyl and amino groups which are able to form strong intermolecular and intramolecular hydrogen bonds [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs it can be seen in the XRD pattern of PE-0-0, two peaks at 2θ of 21.41 and 23.70 were assigned to the (110) and (200) lattice planes. In Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA, the XRD pattern of PE/CS with different compositions, no obvious peak observed for chitosan. The result confirms that CS was exfoliated in the polymer matrix. Furthermore, the CS content has no significant effect on the crystal size of PE.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB, the addition of different amounts of AEO did not have a remarkable effect on the crystalline structure of the films. Esfandiari et al. and Suppakul et al. produced LLDPE and LDPE films containing Rosemary essential oil and 1% linalool or methyl chavicol. They found no significant difference in the crystalline structure of the oil loaded films with pure LLDPE or LDPE [\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e]. Therefore, it can be concluded that the presence of CS and AEO up to 7.5% and 10%, respectively, does not have a significant effect on the crystal structure of the polyethylene films.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003e3.3.4 Mechanical properties\u003c/h2\u003e \u003cp\u003ePackaging films need proper mechanical strength and impact resistance during transportation and handling. In order to study the mechanical properties of the prepared films, a tensile test was performed on them. Tensile strength and elongation at break of different samples are shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The elongation at break and tensile strength (PE-5-0 and PE-7.5-0) were decreased significantly by adding CS concerning PE-0-0 (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The Youngs modulus of PE-5-0 and PE-7.5-0 has improved by the introduction of CS particles compared to PE-0-0 (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), due to the rigidity of CS molecules added to the polymer matrix which leads to restrict polymer chains' mobility [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e, \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e]. In addition, improper distribution of CS can be a factor in reducing tensile strength, as CS aggregation can cause film failure even at low stresses[\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Furthermore, thermodynamic immiscibility (weak interfacial adhesion) and intrinsic incompatibility of the polymer chains and CS particles causes decrease in elongation at break as well as tensile strength [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e, \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e, \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCompared to PE-0-0, AEO loading also reduces the tensile strength and the young modulus but increases the elongation at break of PE-5-0 and PE-7.5-0 (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). This decrease could be attributed to the AEO discontinuities in the polymer matrix that acts as plasticizer [\u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e]. It means that at low concentrations of AEO, it has discontinuous structure as single droplets. The presence of AEO increases the possibility of polymer chains slippage on each other and, as a result, improves the flexibility and elongation of the films [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e, \u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFor the samples mixed with AEO and CS, compared to PE-0-0, a decrease in the tensile strength and the young modulus is observed (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). However, in PE-7.5-10 sample, by increasing the amount of AEO and the possibility of proper wetting of chitosan, which helps its better distribution in the film, the tensile strength was improved.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe effect of incorporation of CS and AEO on the mechanical properties of the samples.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTensile Strength (MPa)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eElongation at break (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eModulus (MPa)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e879\u0026thinsp;\u0026plusmn;\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e241\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-2.5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.1\u0026nbsp;\u0026plusmn;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e701\u0026thinsp;\u0026plusmn;\u0026thinsp;48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e247\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e601\u0026thinsp;\u0026plusmn;\u0026thinsp;43\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e268\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e527\u0026thinsp;\u0026plusmn;\u0026thinsp;44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e291\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e906\u0026thinsp;\u0026plusmn;\u0026thinsp;41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e211\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e1038\u0026thinsp;\u0026plusmn;\u0026thinsp;51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e201\u0026thinsp;\u0026plusmn;\u0026thinsp;8.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-0-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e1069\u0026thinsp;\u0026plusmn;\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e175\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.1\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e753\u0026thinsp;\u0026plusmn;\u0026thinsp;23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e260\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e824\u0026thinsp;\u0026plusmn;\u0026thinsp;27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e223\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePE-7.5-10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003e948\u0026thinsp;\u0026plusmn;\u0026thinsp;31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e214\u0026thinsp;\u0026plusmn;\u0026thinsp;5.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e \u003ch2\u003e3.3.5 Oxygen transmission rate (OTR)\u003c/h2\u003e \u003cp\u003eTo ensure complete protection of food, it is necessary to minimize the influence of factors that cause spoilage of food. From this point of view, oxygen permeability is one of the factors that can affect the shelf life of food.\u003c/p\u003e \u003cp\u003eOTR analysis was carried out to determine the barrier properties of different samples to permeate oxygen (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The OTR value of the PE-0-0 was found around 1680 cm\u003csup\u003e3\u003c/sup\u003e /m\u003csup\u003e2\u003c/sup\u003e.d.bar. CS incorporation declined OTR values. At 2.5, 5, and 7.5%w/w CS, the OTR of the prepared samples was reduced to 1390, 1100, and 910 cm\u003csup\u003e3\u003c/sup\u003e /m\u003csup\u003e2\u003c/sup\u003e.d.bar, respectively. Chitosan particles in the polymer matrix are able to create a tortuous path that acts as a gas barrier. High tortuosity leads to higher barrier properties and lower permeability [\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs can be seen, there was an increase in OTR values of AEO plastic-based samples compared to the PE-0-0, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The incorporation of AEO increased OTR value to 1880 in PE-0-5 and 2064 cm\u003csup\u003e3\u003c/sup\u003e /m\u003csup\u003e2\u003c/sup\u003e.d.bar in PE-0-7.5 film. The rise in OTR values is not surprising owing to the alteration of film structure in the presence of AEO as a result of two interrelated causes[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e]. AEO at first, because of its nature, could dissolve and migrate to the amorphous region of the film. Nevertheless, after saturation of the amorphous region, AEO starts to interpose with the polymer-polymer interactions, leading to an increase in the OTR property of the plastic films. Second, the plasticizing effect of the active oil causes an increase in the polymer chains mobility and consequently decreases the resistance of samples to oxygen diffusion. In the case of CS/AEO loaded samples, two opposing trends could be observed simultaneously. From one side, the presence of CS molecules restricts oxygen flow, and on the other hand, the rising free volume in the film structure as a result of chemical interaction between AEO and polymer chains reinforce oxygen permeability[\u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e74\u003c/span\u003e]. As can be seen, OTR values increased in all samples because of the predominating effect of AEO incorporation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e \u003ch2\u003e3.3.6 Thermal behavior\u003c/h2\u003e \u003cp\u003eThermal stability is one of the important characteristics in packaging films as they may undergo heat processes within production, distribution, and storage[\u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e75\u003c/span\u003e, \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e76\u003c/span\u003e]. In this study, this method was also used to determine the remaining AEO in the films after processing. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA shows TGA thermograms of AEO, CS, PE-0-10 and PE-7.5-10. The result of the CS thermal degradation test, as mentioned in the literature, showed two separate weight losses[\u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e77\u003c/span\u003e]. The first weight loss step of about 5%, that takes place before 150\u0026deg;C, is related to the evaporation of the absorbed water. The main degradation was observed between 250 and 400\u0026deg;C, with a weight loss of about 50%. Hence, CS shows resistance to thermal degradation up to the processing temperatures. For the next steps and preparation of the compounds, CS was subjected to thermal treatment for 5 h at 70\u0026deg;C to remove the absorbed water.\u003c/p\u003e \u003cp\u003eAs shown in the Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA, AEO is evaporated completely till 160 \u0026ordm;C. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA for the sample PE-0-10 shows a two-step degradation process in the temperature ranges of 50\u0026ndash;200 and 420\u0026ndash;530\u0026deg;C which are related to AEO evaporation and polymer matrix degradation, respectively. The result indicates that at 160 and 250 ˚C more than 7% and almost all of AEO loaded in the film evaporates, respectively.\u003c/p\u003e \u003cp\u003eThree distinct thermal degradation steps are detectable for the sample PE-7.5-10. The initial weight loss for temperatures less than 250\u0026deg;C is attributed to the volatilization of AEO and the second step related to the decomposition of CS. As a result of composite fabrication, the CS degradation temperature has increased from 250 to 290\u0026deg;C. The remarkable thing is that with the addition of chitosan to the system, the durability of AEO in the film increased and up to 200\u0026deg;C only about 3% of the oil was evaporated. The reason can be attributed to the surface adsorption of AEO on CS, which leads to more loading of the oil in the film. This data is in full agreement with the result of GC-Mass test.\u003c/p\u003e \u003cp\u003eTherefore, the method of adsorption of AEO on CS particles can retain the essential oil more than the direct method of adding AEO and mixing with polyethylene granules in the final film.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003e3.3.7 Scanning electron microscopy (SEM) analysis\u003c/h2\u003e \u003cp\u003eElectron microscopic images of the cross-section of the samples containing the maximum values of CS and AEO, individually, and the both are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB (1\u0026ndash;3). Figure\u0026nbsp;6B1 illustrates the morphology of sample PE-0-10. The Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB\u003cb\u003e3\u003c/b\u003e shows a relatively continuous distribution of AEO in the polymer matrix. On the other hand, Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB\u003cb\u003e2\u003c/b\u003e indicates improper distribution of CS and its aggregations in the polymer matrix. While, with the help of wetting chitosan with the oil, the distribution of CS in the polymer matrix is ​​greatly improved, which is confirmed by the results of mechanical properties.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003e3.3.8 Antibacterial activity of the films\u003c/h2\u003e \u003cp\u003eSince the purpose of this research is to prepare antibacterial PE films for food packaging, the antibacterial test was performed on the samples containing the maximum amounts of AEO and CS, as well as the sample containing the both components. Antibacterial studies were conducted using the agar disc diffusion method, which presents a qualitative evaluation of the antibacterial properties of the samples. In this respect, when the polymeric films containing the antibacterial agent are placed on top of the culture media, it is expected that the active agent diffuse from the bulk of the film into the agar in a radial manner, developing a clear zone of growth inhibition surrounding the sample[\u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e]. Typical results of these tests for different samples are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. The ratio of the clear zone area to the sample area was adopted to show the antibacterial activity of the active films.\u003c/p\u003e \u003cp\u003eAs expected, the control sample (PE-0-0) did not exhibit antibacterial activity against any of the tested bacteria. Also, samples with 5 and 7.5% CS did not reveal antibacterial activity, and they showed neither inhibition nor retraction zone, because CS is enclosed in the polymer matrix and has no migration to the surface (physiochemical properties of CS) [\u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e78\u003c/span\u003e, \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e79\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFurther, Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e illustrates the inhibition zones of active films impregnated with AEO against tested microorganisms. The result indicates that sample PE-7.5-10 shows more antibacterial property than PE-0-10, it is due to the presence of CS in the sample, which causes less AEO evaporation from the composite during film production process by adsorption of AEO. The constituents of AEO, thymol and carvacrol, have polar functional groups[\u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e80\u003c/span\u003e, \u003cspan citationid=\"CR81\" class=\"CitationRef\"\u003e81\u003c/span\u003e], including hydroxyl groups which could probably interact with CS chains through hydrogen bond and improve the resistance of AEO against harsh processing conditions. These findings emphasize the crucial function of CS particles as active carrier of the volatile component of AEO.\u003c/p\u003e \u003cp\u003eThe antibacterial properties of EOs containing high levels of thymol and/or carvacrol have been described by many researchers[\u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e82\u003c/span\u003e], which is attributed to their ability to permeate and depolarize the cytoplasmic membrane. Thymol and carvacrol interact with the lipid bilayer of the bacterial cytoplasmic membrane led to a loss of integrity, releasing the lipopolysaccharides, and hence, increasing the permeability of the adenosine triphosphate in the cytoplasmic membrane, and consequently, change the passive permeability of the cell and leakage of the cellular material such as ions and nucleic acid[\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e, \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e83\u003c/span\u003e]. Most authors have reported that Gram-negative bacteria are more resistant than Gram-positive ones using different EOs[\u003cspan citationid=\"CR84\" class=\"CitationRef\"\u003e84\u003c/span\u003e]. The higher resistance of Gram-negative bacteria to the antibacterial activity of EOs could be assigned to the external layer that encircles the wall of the lipopolysaccharides in these bacterial species, limiting the diffusion of hydrophobic constituents[\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. However, our findings revealed higher effectiveness of AEO against E. coli, which is categorized as Gram-negative bacteria. Other studies have reported the same result additionally[\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Consequently, it can be concluded that experimental conditions for antibacterial analysis are vital to get high or low sensitivity of specific bacteria species against active compounds.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4 Conclusion","content":"\u003cp\u003eThe purpose of this study is to prepare antibacterial food packaging films based on AEO and improve the performance of the antibacterial agent by using chitosan as an absorbent. Characteristic parameters of the films such as mechanical properties, thermal stability, OTR and anti-bacterial activity have been successfully studied as well as chitosan's ability to absorb AEO. First, variation in the surface adsorption of three main components in AEO (thymol, ρ-cymene, and γ-terpinene) on chitosan was investigated. The optimal time for proper physical interaction between AEO and CS particles and anchoring of AEO molecules on chitosan was calculated about 6 hours. The results of TGA tests of the films prepared with maximum amounts of AEO, CS and the both, PE-7.5.0, PE-0-10, PE-7.5-10 showed that the presence of CS reduces the evaporation of oil (from 7% in PE-0-10 to 3% for PE-7.5-10) during the film formation process. In addition, the tensile test results show that after incorporation of AEO and CS, the modulus and tensile strength of sample PE-7.5-10 were 224 and 14.5 MPa, respectively, and the elongation at break was about 948%, which shows the films still has good mechanical properties for food packaging. The value of OTR for PE-7.5-10 sample was calculated 1500, while, the value for PE-0-0 measured 1680 cm\u003csup\u003e3\u003c/sup\u003e/m\u003csup\u003e2\u003c/sup\u003e.day.bar, which is a significant reduction. The consequence of antibacterial inhibition zone tests illustrates that the control sample, (PE-0-0 film), did not show antibacterial activity against any of the gram-positive (S. Aureus) and gram-negative (E. coli) bacteria, as well as PE-7.5-0 sample. Also, PE-0-10 exhibited relative resistance against E. coli and S. aureus bacteria, whenever, PE-7.5-10 sample showed high antibacterial resistance. The results emphasize the vital function of CS particles as active carriers of AEO volatile component. Therefore, it can be said that the sample containing the highest amounts of CS and AEO, due to its excellent antibacterial properties and acceptable mechanical properties, can be a good candidate for use in food packaging.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthical Statements:\u003c/strong\u003e \u003cp\u003eEthical approval: Not Applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to participate:\u003c/strong\u003e \u003cp\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003econsent to publish:\u003c/strong\u003e \u003cp\u003eAll the authors of manuscript declare their consent to print and publish the article.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis work was supported by Iran Polymer and Petrochemical Institute (Grant No.23794109).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eFarhid Farahmand conceived of the presented idea. Farhid Farahmnad and Jalil Morshedian developed the theory and performed the computations. Kasra Shiva and Adel Soleimani verified the analytical methods. Farhid Farahmand encouraged Adel Soleimani and Kasra Shiva to investigate on the results of adsorption and supervised the findings of this work. Adel Soleimani took the lead in writing the manuscript. All authors discussed the results and contributed to the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePeng, B., et al.: \u003cem\u003eRecent Advances in Nanomaterials-Enabled Active Food Packaging: Nanomaterials Synthesis, Applications and Future Prospects.\u003c/em\u003e Food Control, : p. 110542. (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGanjeh, A.M., et al.: Recent advances in nano-reinforced food packaging based on biodegradable polymers using layer-by-layer assembly: A review. Carbohydr. Polym. Technol. Appl., : p. 100395. (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNouri, M., et al.: \u003cem\u003eInvestigation of LLDPE/LDPE blown films by response surface methodology.\u003c/em\u003e (2006)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoleimani, A., et al.: Silver/Hydrogen-Exchanged Zeolites Embedded in Modified Polyethylene Blends for Antibacterial Packaging with Prolonged Color Stability. ACS Appl. Polym. Mater. \u003cb\u003e5\u003c/b\u003e(4), 2917\u0026ndash;2930 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYao, Q., et al.: Polysaccharide-based food packaging and intelligent packaging applications: A comprehensive review, p. 104390. Trends in Food Science \u0026amp; Technology (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, K., et al.: Preparation and characterization of chitosan/dialdehyde carboxymethyl cellulose composite film loaded with cinnamaldehyde@ zein nanoparticles for active food packaging. Int. J. Biol. Macromol. \u003cb\u003e261\u003c/b\u003e, 129586 (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eValderrama, A.C.S., De, G.C.R.: Traceability of active compounds of essential oils in antimicrobial food packaging using a chemometric method by ATR-FTIR. Am. J. Anal. Chem. \u003cb\u003e8\u003c/b\u003e(11), 726 (2017)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNasution, H., et al.: Properties of active packaging of PLA-PCL film integrated with chitosan as an antibacterial agent and syzygium cumini seed extract as an antioxidant agent. Heliyon, \u003cb\u003e10\u003c/b\u003e(1). (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKola, V., Carvalho, I.S.: Plant extracts as additives in biodegradable films and coatings in active food packaging. Food Bioscience, : p. 102860. (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSung, S.-Y., et al.: Control of bacteria growth on ready-to-eat beef loaves by antimicrobial plastic packaging incorporated with garlic oil. Food Control. \u003cb\u003e39\u003c/b\u003e, 214\u0026ndash;221 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrandelli, A.: \u003cem\u003eNanobiotechnology strategies for delivery of antimicrobials in agriculture and food\u003c/em\u003e, in \u003cem\u003eNanotechnologies in food and agriculture\u003c/em\u003e, pp. 119\u0026ndash;139. Springer (2015)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim, M.J., et al.: Preparation of poly (vinyl alcohol)/silver-zeolite composite hydrogels by UV-irradiation. Fibers Polym. \u003cb\u003e15\u003c/b\u003e(1), 101\u0026ndash;107 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAldalbahi, A., et al.: Fabrication of biodegradable and antibacterial films of chitosan/polyvinylpyrrolidone containing Eucalyptus citriodora extracts. Int. J. Biol. Macromol. \u003cb\u003e266\u003c/b\u003e, 131001 (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZheng, H., et al.: Poly-(lactic acid) composite films comprising carvacrol and cellulose nanocrystal\u0026ndash;zinc oxide with synergistic antibacterial effects. Int. J. Biol. Macromol. \u003cb\u003e266\u003c/b\u003e, 130937 (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKuplennik, N., et al.: Antimicrobial packaging based on linear low-density polyethylene compounded with potassium sorbate. LWT-Food Sci. Technol. \u003cb\u003e62\u003c/b\u003e(1), 278\u0026ndash;286 (2015)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLee, C.H., et al.: A coating for use as an antimicrobial and antioxidative packaging material incorporating nisin and α-tocopherol. J. Food Eng. \u003cb\u003e62\u003c/b\u003e(4), 323\u0026ndash;329 (2004)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDevlieghere, F., et al.: The effectiveness of hexamethylenetetramine-incorporated plastic for the active packaging of foods. Packaging Technol. Sci. \u003cb\u003e13\u003c/b\u003e(3), 117\u0026ndash;121 (2000)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMousavian, D., et al.: Physicomechanical properties, release kinetics, and antimicrobial activity of activated low-density polyethylene and orientated polypropylene films by Thyme essential oil active component. J. Food Meas. Charact. \u003cb\u003e15\u003c/b\u003e, 883\u0026ndash;891 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOrdon, M., et al.: Polyethylene films containing plant extracts in the polymer matrix as antibacterial and antiviral materials. Int. J. Mol. Sci. \u003cb\u003e22\u003c/b\u003e(24), 13438 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoradi, E., et al.: Prolonging shelf life of chicken breast fillets by using plasma-improved chitosan/low density polyethylene bilayer film containing summer savory essential oil. Int. J. Biol. Macromol. \u003cb\u003e156\u003c/b\u003e, 321\u0026ndash;328 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang, S., Mohammadi, A., Nafchi, Baghaie, H.: Development of an active packaging based on polyethylene containing linalool or thymol for mozzarella cheese, vol. 9, pp. 3732\u0026ndash;3739. Food science \u0026amp; nutrition (2021). 7\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHeras, M., et al.: Trends in chitosan-based films and coatings: A systematic review of the incorporated biopreservatives, biological properties, and nanotechnology applications in meat preservation. Food Packaging Shelf Life. \u003cb\u003e42\u003c/b\u003e, 101259 (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSiddiqui, M.N., et al.: Development of bio-composites with enhanced antioxidant activity based on poly (lactic acid) with thymol, carvacrol, limonene, or cinnamaldehyde for active food packaging. Polymers. \u003cb\u003e13\u003c/b\u003e(21), 3652 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMotelica, L., et al.: Antibacterial biodegradable films based on alginate with silver nanoparticles and lemongrass essential oil\u0026ndash;innovative packaging for cheese. Nanomaterials. \u003cb\u003e11\u003c/b\u003e(9), 2377 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMotelica, L., et al.: Innovative antimicrobial chitosan/ZnO/Ag NPs/citronella essential oil nanocomposite\u0026mdash;Potential coating for grapes. Foods. \u003cb\u003e9\u003c/b\u003e(12), 1801 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoazeni, M., Saharkhiz, M.J., Hosseini, A.A.: In vitro lethal effect of ajowan (Trachyspermum ammi L.) essential oil on hydatid cyst protoscoleces. Vet. Parasitol. \u003cb\u003e187\u003c/b\u003e(1\u0026ndash;2), 203\u0026ndash;208 (2012)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOmidpanah, S., et al.: Effects of Monoterpenes of Trachyspermum ammi on the Viability of Spermatogonia Stem Cells In Vitro. Plants (Basel). \u003cb\u003e9\u003c/b\u003e(3), 343 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSivaram, S., et al.: The beneficial role of plant based thymol in food packaging application: A comprehensive review. Appl. Food Res. \u003cb\u003e2\u003c/b\u003e(2), 100214 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdnan, M., et al.: Review on antibacterial activity of Himalayan medicinal plants traditionally used to treat pneumonia and tuberculosis. J. Pharm. Pharmacol. \u003cb\u003e71\u003c/b\u003e(11), 1599\u0026ndash;1625 (2019)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-Gebaly, A.S., et al.: Combination of nanoparticles (NPs) and essential oils (EOs) as promising alternatives to non-effective antibacterial, antifungal and antiviral agents: A review. Biocatal. Agric. Biotechnol., : p. 103067. (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBasavegowda, N., Baek, K.-H.: Synergistic antioxidant and antibacterial advantages of essential oils for food packaging applications. Biomolecules. \u003cb\u003e11\u003c/b\u003e(9), 1267 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTian, B., et al.: Biopolymer food packaging films incorporated with essential oils. J. Agric. Food Chem. \u003cb\u003e71\u003c/b\u003e(3), 1325\u0026ndash;1347 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEbrahimzadeh, S., et al.: Incorporation of essential oils in edible seaweed-based films: A comprehensive review. Trends in Food Science \u0026amp; Technology (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStrasakova, M., et al.: Immobilization of caraway essential oil in a polypropylene matrix for antimicrobial modification of a polymeric surface. Polymers. \u003cb\u003e13\u003c/b\u003e(6), 906 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHashim, R., et al.: \u003cem\u003eEffects of incorporation of essential oil into film for fruit packaging application\u003c/em\u003e. in \u003cem\u003eIOP Conference Series: Earth and Environmental Science\u003c/em\u003e. IOP Publishing. (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMin, T., et al.: Electrospun pullulan/PVA nanofibers integrated with thymol-loaded porphyrin metal-organic framework for antibacterial food packaging. Carbohydr. Polym. \u003cb\u003e270\u003c/b\u003e, 118391 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDaramola, O., et al.: \u003cem\u003eMechanical properties of high density polyethylene matrix composites reinforced with chitosan particles.\u003c/em\u003e Materials Today: Proceedings, 38: pp. 682\u0026ndash;687. (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVerma, D.K., et al.: Synthesis, characterization and applications of chitosan based metallic nanoparticles: A review. J. Appl. Nat. Sci. \u003cb\u003e13\u003c/b\u003e(2), 544\u0026ndash;551 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMouhoub, A., et al.: Assessment of the antioxidant, antimicrobial and antibiofilm activities of essential oils for potential application of active chitosan films in food preservation. World J. Microbiol. Biotechnol. \u003cb\u003e38\u003c/b\u003e(10), 179 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBi, J., et al.: Novel procyanidins-loaded chitosan-graft-polyvinyl alcohol film with sustained antibacterial activity for food packaging. Food Chem. \u003cb\u003e365\u003c/b\u003e, 130534 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNostro, A., et al.: Study on carvacrol and cinnamaldehyde polymeric films: mechanical properties, release kinetics and antibacterial and antibiofilm activities. Appl. Microbiol. Biotechnol. \u003cb\u003e96\u003c/b\u003e(4), 1029\u0026ndash;1038 (2012)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSolano, A.C.V., de Gante, C.: \u003cem\u003eTwo different processes to obtain antimicrobial packaging containing natural oils.\u003c/em\u003e Food and Bioprocess Technology, 5(6): pp. 2522\u0026ndash;2528. (2012)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSung, S.-Y., et al.: Effects of Allium sativum essence oil as antimicrobial agent for food packaging plastic film. Innovative Food Sci. Emerg. Technol. \u003cb\u003e26\u003c/b\u003e, 406\u0026ndash;414 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWattananawinrat, K., Threepopnatkul, P., Kulsetthanchalee, C.: Morphological and thermal properties of LDPE/EVA blended films and development of antimicrobial activity in food packaging film. Energy Procedia. \u003cb\u003e56\u003c/b\u003e, 1\u0026ndash;9 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuarda, A., et al.: The antimicrobial activity of microencapsulated thymol and carvacrol. Int. J. Food Microbiol. \u003cb\u003e146\u003c/b\u003e(2), 144\u0026ndash;150 (2011)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEsmaeili, A., Asgari, A.: vitro release and biological activities of Carum copticum essential oil (CEO) loaded chitosan nanoparticles. Int. J. Biol. Macromol. \u003cb\u003e81\u003c/b\u003e, 283\u0026ndash;290 (2015)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eQuiroz-Castillo, J.M., et al.: Preparation of extruded polyethylene/chitosan blends compatibilized with polyethylene-graft-maleic anhydride. Carbohydr. Polym. \u003cb\u003e101\u003c/b\u003e, 1094\u0026ndash;1100 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTonekaboni, H.B., Mehdikhani, S., Yazdani, H.: Fabricating chitosan/low-density polyethylene (CS-LDPE) films and its efficacy to prolong shelf life of rainbow trout fish. Food Bioscience. \u003cb\u003e57\u003c/b\u003e, 103401 (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBasij, M., et al.: Insecticidal potential of Ajwain essential oil and its major components against Chilo suppressalis Walker. J. Plant Dis. Prot. \u003cb\u003e130\u003c/b\u003e(4), 735\u0026ndash;745 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShabani, M., et al.: Long-lasting adsorption of golden flower oil on polyvinyl alcohol/clinoptilolite (PVA/CP) xerogel particles. Appl. Clay Sci. \u003cb\u003e195\u003c/b\u003e, 105699 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang, Y., et al.: Chitosan nanocarriers containing essential oils as a green strategy to improve the functional properties of chitosan: A review. Int. J. Biol. Macromol. \u003cb\u003e236\u003c/b\u003e, 123954 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDutta, S., et al.: Characterization, antifungal properties and in silico modelling perspectives of Trachyspermum ammi essential oil. Lwt. \u003cb\u003e131\u003c/b\u003e, 109786 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVan Krevelen, D.W., Te, K., Nijenhuis: Properties of polymers: their correlation with chemical structure; their numerical estimation and prediction from additive group contributions. Elsevier (2009)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eReesha, K.V., et al.: Development and characterization of an LDPE/chitosan composite antimicrobial film for chilled fish storage. Int. J. Biol. Macromol. \u003cb\u003e79\u003c/b\u003e, 934\u0026ndash;942 (2015)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYarnpakdee, S., et al.: Extraction and physico\u0026ndash;chemical characterization of chitosan from mantis shrimp (Oratosquilla nepa) shell and the development of bio-composite film with agarose. Polymers. \u003cb\u003e14\u003c/b\u003e(19), 3983 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBasu, A., et al.: Edible nano-bio-composite film cargo device for food packaging applications. Food Packaging Shelf Life. \u003cb\u003e11\u003c/b\u003e, 98\u0026ndash;105 (2017)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHadi, A.G., et al.: \u003cem\u003eExtraction and characterization of Chitosan gained from oyster and fish shells and evaluation its application as antioxidant\u003c/em\u003e. in \u003cem\u003eAIP Conference Proceedings. AIP Publishing LLC\u003c/em\u003e. (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYusuf, Y., Arman, B., Cahyana, A.H.: Syntheses via phenolic oxidative coupling using crude peroxidase from Brassica juncea (L) Czern leaves and antioxidant evaluation of dimeric thymol. Mediterranean J. Chem. \u003cb\u003e3\u003c/b\u003e(6), 1100\u0026ndash;1110 (2015)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAhmad, A.L., Sumathi, S., Hameed, B.H.: Adsorption of residue oil from palm oil mill effluent using powder and flake chitosan: equilibrium and kinetic studies. Water Res. \u003cb\u003e39\u003c/b\u003e(12), 2483\u0026ndash;2494 (2005)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMa, Y., et al.: Preparation, characterization, in vitro release, and antibacterial activity of oregano essential oil chitosan nanoparticles. Foods. \u003cb\u003e11\u003c/b\u003e(23), 3756 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHan, X., et al.: Preparation, characterization and antibacterial activity of new ionized chitosan. Carbohydr. Polym. \u003cb\u003e290\u003c/b\u003e, 119490 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZidan, T., Abdelhamid, A.E., Zaki, E.: N-Aminorhodanine modified chitosan hydrogel for antibacterial and copper ions removal from aqueous solutions. Int. J. Biol. Macromol. \u003cb\u003e158\u003c/b\u003e, 32\u0026ndash;42 (2020)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi, B., et al.: Synthesis, characterization, and antibacterial activity of cross-linked chitosan-glutaraldehyde. Mar. Drugs. \u003cb\u003e11\u003c/b\u003e(5), 1534\u0026ndash;1552 (2013)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEsfandiari, N., et al.: Effect of the Processing Conditions on the Supercritical Extraction and Impregnation of Rosemary Essential Oil in Linear Low-Density Polyethylene Films. Processes. \u003cb\u003e11\u003c/b\u003e(1), 11 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuppakul, P., et al.: Characterization of antimicrobial films containing basil extracts. Packaging Technol. Science: Int. J. \u003cb\u003e19\u003c/b\u003e(5), 259\u0026ndash;268 (2006)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShelly, M., et al.: Structural and free-hole volume characterization of high-density polyethylene-chitosan composites plasticized with palm oil. Polym. Eng. Sci. \u003cb\u003e61\u003c/b\u003e(12), 3060\u0026ndash;3068 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaamoun, A.A., Mahmoud, A.A.: Exploring the mechanical and bacterial prospects of flexible polyurethane foam with chitosan. Cellulose. \u003cb\u003e29\u003c/b\u003e(11), 6323\u0026ndash;6338 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePedroso, A.G., Rosa, D.S.: Mechanical, thermal and morphological characterization of recycled LDPE/corn starch blends. Carbohydr. Polym. \u003cb\u003e59\u003c/b\u003e(1), 1\u0026ndash;9 (2005)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDong, Z., et al.: Characterization and preservation performance of active polyethylene films containing rosemary and cinnamon essential oils for Pacific white shrimp packaging. Food Control. \u003cb\u003e92\u003c/b\u003e, 37\u0026ndash;46 (2018)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShakour, N., et al.: Investigating the properties of PLA-nanochitosan composite films containing Ziziphora Clinopodioides essential oil and their impacts on oxidative spoilage of Oncorhynchus mykiss fillets, vol. 9, pp. 1299\u0026ndash;1311. Food Science \u0026amp; Nutrition (2021). 3\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShankar, S., Khodaei, D., Lacroix, M.: Effect of chitosan/essential oils/silver nanoparticles composite films packaging and gamma irradiation on shelf life of strawberries. Food Hydrocoll. \u003cb\u003e117\u003c/b\u003e, 106750 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIdris, A., et al.: A review on predictive tortuosity models for composite films in gas barrier applications. J. Coat. Technol. Res., : p. 1\u0026ndash;18. (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamos, M., et al.: Characterization and antimicrobial activity studies of polypropylene films with carvacrol and thymol for active packaging. J. Food Eng. \u003cb\u003e109\u003c/b\u003e(3), 513\u0026ndash;519 (2012)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMart\u0026iacute;nez-Tenorio, Y., et al.: Development of Antifungal Packaging From Low‐Density Polyethylene With Essential Oil of Oregano and Potassium Sorbate. Packaging Technology and Science (2024)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSharma, S., et al.: Essential oils as additives in active food packaging. Food Chem. \u003cb\u003e343\u003c/b\u003e, 128403 (2021)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSalmas, C.E., et al.: Development and evaluation of a novel-thymol@ natural-zeolite/low-density-polyethylene active packaging film: Applications for pork fillets preservation. Antioxidants. \u003cb\u003e12\u003c/b\u003e(2), 523 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTan, W., et al.: Design, synthesis of novel chitosan derivatives bearing quaternary phosphonium salts and evaluation of antifungal activity. Int. J. Biol. Macromol. \u003cb\u003e102\u003c/b\u003e, 704\u0026ndash;711 (2017)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLim, S.H., Hudson, S.M.: Synthesis and antimicrobial activity of a water-soluble chitosan derivative with a fiber-reactive group. Carbohydr. Res. \u003cb\u003e339\u003c/b\u003e(2), 313\u0026ndash;319 (2004)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOladzadabbasabadi, N., et al.: Recent advances in extraction, modification, and application of chitosan in packaging industry. Carbohydr. Polym. \u003cb\u003e277\u003c/b\u003e, 118876 (2022)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang, L., et al.: Antibacterial food packaging capable of sustained and unidirectional release carvacrol/thymol nanoemulsions for pork preservation. Food Hydrocoll. \u003cb\u003e145\u003c/b\u003e, 109169 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCasalini, S., Giacinti, M., Baschetti: The use of essential oils in chitosan or cellulose-based materials for the production of active food packaging solutions: a review. J. Sci. Food. Agric. \u003cb\u003e103\u003c/b\u003e(3), 1021\u0026ndash;1041 (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHajibonabi, A., et al.: \u003cem\u003eAntimicrobial activity of nanoformulations of carvacrol and thymol: New trend and applications.\u003c/em\u003e OpenNano, : p. 100170. (2023)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRamos, M., et al.: Development of novel nano-biocomposite antioxidant films based on poly (lactic acid) and thymol for active packaging. Food Chem. \u003cb\u003e162\u003c/b\u003e, 149\u0026ndash;155 (2014)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlsakhawy, S.A., et al.: \u003cem\u003eComparative Phytochemical Composition and Antimicrobial Activity of Citrus Peel Essential Oils and Phenolic Compounds.\u003c/em\u003e Anti-Infective Agents, 21(4): pp. 57\u0026ndash;68. For the TOC Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films \u003cem\u003eKasra Shiva\u003c/em\u003e\u003csup\u003e\u003cem\u003e1\u003c/em\u003e,\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e, \u003cem\u003eAdel Soleimani\u003c/em\u003e\u003csup\u003e\u003cem\u003e1\u003c/em\u003e,\u003cem\u003e2\u003c/em\u003e\u003c/sup\u003e, \u003cem\u003eJalil Morshedian\u003c/em\u003e\u003csup\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sup\u003e, \u003cem\u003eFarhid Farahmandghavi\u003c/em\u003e\u003csup\u003e\u003cem\u003e2\u003c/em\u003e,\u003c/sup\u003e, \u003cem\u003eand Fatemeh Shokrolahi\u003c/em\u003e\u003csup\u003e\u003cem\u003e3\u003c/em\u003e 1\u003c/sup\u003eDepartment of Polymer Processing, Faculty of Processing, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran \u003csup\u003e2\u003c/sup\u003eDepartment of Novel Drug Delivery Systems, Faculty of Science, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran \u003csup\u003e3\u003c/sup\u003eDepartment of Biomaterials, Faculty of Science, Iran Polymer and Petrochemical Institute, P.O. Box: 14965/115, Tehran, Iran (2023)\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Antibacterial Packaging, Low-density polyethylene, Chitosan, Ajwain Essential oil","lastPublishedDoi":"10.21203/rs.3.rs-4548087/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4548087/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this research, we prepared an antibacterial packaging composite film for food packaging. Ajwan essential oil (AEO) was adsorbed onto chitosan (CS) particles, which were loaded in a combination of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene graft-maleic anhydride (PEma, 4%). Gas chromatography (GC) results confirmed successful AEO adsorption on chitosan particles, with protection from evaporation during the film formation process. Additionally, inhibition zone (IZ) tests demonstrated increased antibacterial activity in the film. Mechanical tests revealed that AEO incorporation decreased tensile strength but increased elongation at break, while CS reduced elongation at break. CS particles in PE-7.5-0 (910 cm\u0026sup3;/m\u0026sup2;\u0026middot;day\u0026middot;bar) reduced oxygen permeability compared to PE-0-0 (1680 cm\u0026sup3;/m\u0026sup2;\u0026middot;day\u0026middot;bar), but adding AEO increased oxygen permeability (PE-0-10, 2200 cm\u0026sup3;/m\u0026sup2;\u0026middot;day\u0026middot;bar). The antibacterial activity results indicated a synergistic inhibitory effect of CS and AEO. The composite film containing 7.5% chitosan and 10% adsorbed AEO (PE-7.5-10) exhibited suitable mechanical properties and improved antibacterial behavior due to AEO adsorption on CS. Consequently, it can be considered a suitable candidate for food packaging.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e","manuscriptTitle":"Absorption of Ajwain Essential Oil on Chitosan to Enhance Antibacterial Activity of Polyethylene-based Composite Food Packaging Films","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-25 05:26:52","doi":"10.21203/rs.3.rs-4548087/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9efaeda4-9b41-43d8-9f97-c6676e365554","owner":[],"postedDate":"June 25th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-06-27T19:54:27+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-25 05:26:52","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4548087","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4548087","identity":"rs-4548087","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}