Non-thermal shelf-life extension of fresh Hummus by High Hydrostatic Pressure and refrigeration

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Results showed that a treatment of HHP at 600MPa for 6 minutes was able to achieve more than 5 log reductions of the tested pathogens, and about 4 logs for aerobic plate count (APC) and Yeast and Mold (YM), respectively. Moreover, pathogens remained undetectable during the period of refrigerated storage for 1 year, while APC and YM were increased to log 2.32 and <1 log, respectively. After 52 weeks of refrigerated storage, HHP treated samples showed no significant differences in respect to sensorial properties of hummus samples and remained microbiologically within the “High quality” standards according to the microbiological criteria of ready to eat foods. High hydrostatic pressure non-thermal preservation ready-to-eat minimally processed shelf life Hummus Industrial application HHP at 600 MPa for 6 minutes in combination with refrigeration ≤5°C was able to achieve more than 5 logs reduction for certain pathogens associated with numerous Hummus outbreaks. The combined treatment extended the shelf life for about 1 year (52 weeks) without using of chemical preservatives or post-filling heat treatment. This hurdle combination would be an appropriate alternative for the industrial sector to the commercial sterilization of Hummus by heat treatment. Introduction Hummus, a ready to eat food, is produced by mixing finely ground cooked chickpeas ( Cicer arietinum L) with sesame paste, salt and acidulant like fresh lemon juice or citric acid as the main ingredients, though, garlic, basil, paprika, red pepper, jalapeno, and olive oil are added to give variety of flavours. Thanks to its main components, considering the variation in recipes, the nutritional value of this vegetarian product is rich due to the high contents of protein (6–10%) and unsaturated fat (8–12%), and supplies 166 calories per 100 grams which makes it a cheap source of nutrients (The food processor, 2011). Hummus had attracted the consumers around the world in the recent decades despite it was originated in the Levant, and it has expanded in many European countries, United States and Canada (Al-Qadiri et al., 2020 ). As a ready-to- eat food, the microbial criteria of Hummus shall meet those set by the Jordanian Food and Drug Administration (JFDA, 2011). The microbial criteria stipulate that Aerobic Plate Count (APC) should not exceed 10 6 colony forming unit per gram (cfu/g), while Listeria monocytogenes , Salmonella and Escherichia coli O157:H7 shall not be detected in 25 grams sample for such foods to be classified as “High Quality”. The microbial load of Hummus is low due to its preparation method, in which the Chickpeas are boiled. Moreover, Tahini (sesame paste) which is the second main component is classified as a low-risk food due to its low water activity, and the effect of heat during roasting and grinding of sesame seeds. Tahihi still contains some viable microorganisms which could grow when water activity increased to suitable levels upon its incorporation in products having high moisture levels like Hummus (Yamani and Isa, 2006 ). Therefore, the initial microbial quality of Hummus is directly influenced by its ingredients, preparation steps, storage conditions, display, and dispensing environment (Al-Holy, et al., 2006 ). Hummus is generally produced and consumed fresh at households and in restaurants with shelf life of few days under refrigeration (Karam, et al. 2023 ). In the past few years, markets have had fresh Hummus packed in press-to-seal plastic containers kept under refrigeration with chemical preservatives having shelf life up to one month. The commercially- sterilized product packed in metal cans has been produced for many decades in which the product is subjected to high temperature for long time. Recently, the advanced packaging solutions allowed food industry to produce aseptically filled flexible containers in which the product is subjected to high heat treatment. Although this thermally- treated products has a shelf life of one to two years, its flavour, colour, nutritional and other organoleptic properties are somewhat inferior to the fresh product (Amr, et al.,2017). Consequently, there is a need to produce and preserve the product in such a way to render it not only safe but also to maintain its good nutritional, freshness, and sensory qualities without compromising its shelf life, especially with the increasing demand for fresher, preservatives free and minimally processed foods. Several methods can satisfy this objective especially the non-thermal ones like high hydrostatic pressure, pulsed electrical field, refrigeration and irradiation or a combination of two or more methods (Shahein, et al., 2023 ; Juneja, 2003 ). High Hydrostatic pressure processing (HHP) is an emerging preservation technology that employs the pressures in the range of 100–800 MPa with or without the application of heat, and it is usually applied to pre-packaged food items (Shahein, et al., 2023 ; Usage, et al., 2021). The application of HHP in combination with one or more processing method such as refrigeration is growing and may expand significantly with the development of high-pressure system fabrication. Some research work was conducted to utilise HHP technology to ensure safety of ready to eat foods and to extend their shelf life. Salazar et al. ( 2019 ) investigated the effect of 350MPa for exposure time of 4 minutes and found that Listeria monocytogenes count was reduced from 6.85 Log to 4.27 Log inducing only 2.58 Log reduction. Shahein et al., ( 2023 ) studied the effects of HHP of 600 MPa from 1 to 6 minutes against L. monocytogenes, Staphylococcus aureus and E. coli in low salt white cheese to determine the D 600MPa Value and revealed that L. monocytogenes was not detected after 4 minutes of application while the, S. aureus and E. coli showed survivors of 2.69 and 2.26 log cfu/g after 6 minutes exposure which disclose the significance of longer exposure time specially against S. aureus and E. coli . Accordingly, the objective of this work was to study the effect of the high hydrostatic pressure treatment of 600MPa for 6 minutes on several pathogens in fresh Hummus, and the possibility of extending the shelf life up to one year (52 weeks) under refrigerated storage. Materials and methods 3.1 Microbial strain preparation Freeze-dried cultures of Listeria monocytogenes (ATCC 13932), Salmonella enterica (ATCC 13314), and Escherichia coli O157:H7 (ATCC 43888) were donated from Secure Vision Laboratory (Amman, Jordan). Each strain freeze-dried bead was rehydrated in 9 mL Brain Heart Infusion – BHI broth (bioMerieux, I’Etoile, France) and incubated for 24 h at 37°C, after which each culture was streaked onto appropriate selective agar and onto Tryptic Soy Agar – TSA (Biokar Diagnostics, Beauvais, France). Selective medias used were Oxford agar (Oxoid, Hampshire, UK), XLD agar (bioMerieux, I’Etoile, France), and Malt extract agar (Merck KGaA, Darmstadt, Germany) for L. monocytogenes , S. enterica , E. coli , respectively. After incubation for 48 h at 37°C the TSA plates were checked for purity while the selective media plates were used to check for typical morphological properties. A single colony of each strain from TSA was inoculated into 9 mL BHI broth in Falcon tube and incubated at 37°C for 24 h. After incubation, each tube was vortexed and centrifuged at 5°C for 10 min at 6000 rpm High Speed Refrigerated Centrifuge (CFGR-18.5JP, Infitek, China). Aseptically, broth was decanted, and the sediment cells were re-suspended into phosphate-buffered saline – PBS (pH 7.2) and centrifuged again. The washing procedure was carried out twice. Finally, the sediment pellet was re-suspended in 20 mL PBS to yield approximate inoculum of 10 8 cfu/mL. The inoculum was stored at 4°C and used within 24 h for Hummus sample inoculation. 3.2 Hummus Sample Preparation A batch of 30 kg of Hummus was prepared according to a recipe used in a local restaurant. The recipe followed is consisted of dry chickpeas 6 kg, Tahini 6 kg, salt 0.24 kg, citric acid 0.210 kg, sodium bicarbonate 0.050 kg and water with ice cubes (around 12 kg) to complete the total weight of 30 kg. The raw materials were acquired from the restaurant and the preparation process was performed at their workshop. Dry chickpeas were sorted and cleaned manually then soaked in potable tap water (in ratio of 1:3) for 8 hours. After straining, the chickpeas were boiled in water with sodium bicarbonate for two hours until get soft. The boiled seeds were precooled with tap water, then spread in a shallow stainless-steel tray and cooled rapidly to 4°C within 90 minutes using an efficient refrigerator. In a high-speed mixer, the cooled seeds were pulverised to a smooth paste and mixed with the other ingredients of Tahini, salt, citric acid, and cold water with ice cubes that had been treated with reverse osmosis unit. The ready Hummus mix was divided into 5 portions of 6 kg, approximately, each for an individual microbial strain inoculation. Preparation process was fully controlled with good hygienic practices. Portions 1 and 2 were not inoculated, while portions 3, 4, and 5 were inoculated separately with 9 mL of microbial strain broth of L. monocytogenes , S. enterica , and E. coli , respectively, and homogenized (L5M-A, Silverson, USA) to reach a count of 10 5 − 1 0 6 cfu/g. After inoculation, each Hummus portion was packed in 60 laminated pouches (Ampac Flexibles, Wolverhampton, UK) with about 100 g each, and kept in an ice box at 0–3°C until HHP treatment. Pouches were made of three layers of Polyethylene Tetra- phthalate, Aluminium foil, and Cast Poly Propylene with thicknesses of 12, 8 and 70 microns. Consequently, five groups (G) of samples were obtained; G 1 and 2 which contain the natural microflora; G3, G4 and G5 were inoculated with L. monocytogenes , S. enterica , and E. coli , respectively. 3.3 HHP treatment High hydrostatic pressure treatment was carried out at a commercial facility in Dubai (Smart Foods Solutions, Dubai, UAE) using a Hyperbaric 55 high pressure processing unit (Condado de Treviño, Burgos, Spain). Samples were retained refrigerated < 5°C until the time of HHP treatment. All Hummus samples, except samples of the G1, were subjected to HHP at 600 MPa for pressure-holding time of 6 min. Water at 12.7 C was used as pressurising medium. 3.4 Microbial Count Aerobic Plate Count (APC) and Yeast and Molds count (YM) were carried out for samples of G1 and G2, while samples of G3, 4 and 5 were investigated for the targeted inoculated pathogens. To determine the initial count, numeration was performed immediately before HHP treatment. While enumeration was carried out after the treatment immediately, at Zero time, and later every 4 weeks up to 52 weeks (1 year). As per ISO method 6887-1:1999, a quantity of 25 ± 1 g thoroughly mixed sample was weighed and transferred aseptically to a dilution bottle containing nine-fold (225 mL) sterile buffered peptone water at ambient temperature to prepare initial suspension. Further decimal dilutions were prepared using 9 mL sterile peptone water at ambient temperature to the final dilution of 10 8 . APC, YM, count of L. monocytogenes, S. enterica and E. coli was conducted as per ISO methods 4833:1-2013, 21527-1:2008, 11290-2:2017, 6579-1:2017 and 16649-2:2001, respectively. 3.5 Chemical analysis Moisture, ash, ether extract (fat) and protein were determined following the methods with numbers 971.28, 942.05, 920.39, 983.14 of AOAC (2011), whereas Nitrogen free extract content (carbohydrates) was estimated mathematically by subtracting sum of protein, fat, ash, and moisture from 100. Titratable acidity and pH were performed following method number 981.12, 942.15 of AOAC 2011). Water activity was measured using Novasina Thermoconstanter Model TH 200 (Novasina, Switzerland). 3.6 Sensory analysis of hummus Sensorial quality evaluation of hummus samples was carried out as described by Lawless and Heymann (2010). A total of 20 (the same 20 panellists for each replicate) habitual hommos consumer panellists were asked to conduct the evaluation procedure with Scores assigned ranged from 1 to 9 indicating dislike extremely to like very much, respectively. Samples of G1 and G2 were included in the evaluation at the first session within 24 hours of HHP treatment, and only samples of G2 were evaluated at week 52. 3.7 Statistical analysis: Statistical analysis of data obtained in this study was performed using SAS statistical program (SASI, 2002). Analysis of Variance (ANOVA) was carried out using the General Liner Model procedure to elucidate the effect of HHP and refrigerated storage on the various quality attributes. Means were separated using Least Significant Difference test (LSD) to compare significance at 5% level of probability ( P ≤ 0.05). The experiments were conducted in duplicate. Results and discussions 4.1 Chemical properties The chemical properties of Hummus samples used in this work are depicted in Table 1 . Hummus is considered a highly perishable ready-to-eat moist food due to its high water activity levels (0.96 ± 0.001) along with the availability of nutrients that support the growth of natural microflora which could affect product stability and its shelf life. Many foodborne pathogens could grow in such water activity (Osaili et al. 2022 ). The minimum level of water activity for the growth of L. monocytogenes, Salmonella , and E. coli is 0.92, 0.94, and 0.95, respectively (Tapia et al. 2020 ; Jay, 2000 ). Fungi could grow in media with a water activity (aw) of 0.8 while many types of yeast could tolerate a level of 0.6 aw (Park, et al., 2014 ). Table 1 Chemical properties of Hummus samples used in this work. Moisture Protein Ether extract Nitrogen free extract Ash pH Acidity% Water activity 66.8 ± 0.28 8.5 ± 0.13 14.3 ± 0.13 8.38± 0.21 1.55 ± 0.07 4.8 ± 0.05 0.85 ± 0.012 0.96 ± 0.001 Each value represents mean of two replicates (N = 2) ± SD. The average pH value found in Hummus was 4.8 categorizes Hummus as a low-acid food. Low-acid foods (pH ≥ 4.6) could support the growth of various microorganisms including toxin-producing pathogens (ICMSF, 1980). Numerous aspects may affect pH including organic acid concentration, temperature, the initial pH of the food, and their buffering capacity which tends to maintain pH levels or arrest their decrease (Derossi, et al., 2011 ). The total acid concentration contained within a food item (originally and added) could be measured by titratable acidity (or total acidity). The initial titratable acidity present in Hummus (0.85% as citric acid) is mainly due to the added citric acid. The added acid reduces the pH value enhances the organoleptic properties and improves its keeping quality, whereas developed acidity is unfavourable in such a product. Reduction in pH value to a certain level that does not impair the organoleptic characteristics could facilitate the preservation of food products. As the pH decreases, inhibitory effects against some microorganisms will occur depending on their minimum pH limit for growth. The reduction in pH could increase the proportion of un-dissociated forms of organic acids present in Hummus mainly citric acid, thus, the efficacy of organic acids as antimicrobial agents will increase (ICMSF, 1980). However, the pH value in Hummus samples used in this work is still insufficient to prevent microbial growth without the application of other hurdles. 4.2 Microbial analysis Table 2 shows the microbial load of samples before and after HHP treatment. Samples of G1 and G2 contained the natural microflora present in Hummus during preparation, whereas the other groups contained inoculated strains. The APC of both G1 and G2 after preparation was 4.71 and 4.76 Logs, while the counts of YM were 3.69 and 3.77 Logs, respectively. APC and YM counts are considered reasonable in such a product since the ingredients are not sterile. Moreover, the product is subjected to several processing steps after boiling and cooling of chickpeas such as grinding and mixing which may increase the microbial load. Low numbers of APC and YM counts reflect the hygienic conditions adopted during the preparation steps and indicate that Hummus samples are complying with the microbial criteria of ready-to-eat foods issued by the Jordanian Food and Drug Administration (JFDA, 2011). Table 2 Microbial count of Hummus samples treated with HHP at 600 MPa for 6 minutes and stored bellow 5°C. Group # Target Microorganism Initial count Log cfu/g HHP treatment Zero-time Log cfu/g Week 4 Log cfu/g Week 8 Log cfu/g Week 12 Log cfu/g Week 42 Log cfu/g Week 44 Log cfu/g Week 48 Log cfu/g Week 52 Log cfu/g G1 APC 4.71 a No Treatment - 6.98 b YM 3.69 a - 7.86 b G2 APC 4.76 a 600MPa for 6 minutes < 1 b < 1 b < 1 b < 1 b < 1 b 1.95 C 2.08 C 2.32 C YM 3.77 a < 1 b < 1 b < 1 b < 1 b < 1 b < 1 b < 1 b < 1 b G3 L. monocytogenes 5.49 a ND b ND b ND b ND b ND b ND b ND b ND b G4 S. enterica 5.61 a ND b ND b ND b ND b ND b ND b ND b ND b G5 E. Coli O157:H7 5.43 a ND b ND b ND b ND b ND b ND b ND b ND b Each value represents the mean of two replicates (N = 2) ± SD. Means in the same row with different superscripts are significantly different at the 5% level of probability ( P ≤ 0.05). Samples of Group 1 were not subjected to HHP treatment, yet they were stored under refrigeration. After 4 weeks of refrigerated storage, the APC and YM showed a significant increase to 6.98 and 7.86 Logs, respectively, which were deemed to be unfit for human consumption according to JFDA microbial criteria (JFDA, 2011). Moreover, spoilage symptoms appeared in the forms of gas holes, sourness, and a putrefactive smell. Concerning G2 samples which contained the natural microflora of Hummus and were subjected to HHP treatment, the results of APC and YM showed a significant decline from 4.76 and 3.77, respectively, to less than 1 Log for both counts. Furthermore, samples were kept refrigerated for a period of 52 weeks and were monitored every 4 weeks against APC and YM. The first significant increase in APC of G2 was shown at week 44 with a count of 1.95 Log. Despite that increase in APC, the YM count remained unchanged till week 52 with less than 1 Log. It is worth noting that plate count < 10 cfu g − 1 was considered as “not detected” and treated statistically as zero. On the other hand, all pathogens inoculated samples of G3, G4, and G5 showed significant reductions to undetectable limits immediately after the HHP treatment. Moreover, samples of Groups 3, 4, and 5 were kept under refrigeration for a period of 52 weeks and tested against the inoculated pathogens every 4 weeks. None of the samples showed a detectable limit of any targeted pathogen, neither L. monocytogenes, S. enterica nor E. coli. These results highlight the impact of HHP treatment of 600 MPa for 6 minutes on the targeted pathogens in Hummus samples of more than 5 logs reduction. Despite that, a sample of each Group (3, 4, and 5) at week 50 was sent to an ISO 17025 accredited external laboratory for microbial detection of the targeted inoculated pathogen as an additional procedure of verification of the results. The L. monocytogenes showed < 10 cfu.g − 1 , E. coli < 0.3 MPN. g − 1 while S. enterica was absent. Results obtained in this work agree with Sokolowska et al. (2019) who reported more than 5 log reduction of L. monocytogenes, Salmonella , and E. coli using the HHP of 500MPa for 10 minutes. Another work conducted by Klog et al. (2018) showed somehow similar results in which the HHP at 550 MPs for 10 minutes induced a reduction in mesophilic, psychrophilic, and Enterobacteriaceae loads that allowed extending the shelf life of broccoli hummus up to 28 days under refrigeration. Alvarez et al. (2017) concluded that the counts of YM and lactic acid bacteria were not detected (less than 2 and 1 Log, respectively) after the HHP treatment of 600MPa for 15 and 25 minutes and remained undetected for a period of 60 days under refrigerated storage. On the other hand, Carminati et. al. ( 2004 ) investigated the efficacy of various combinations of pressure (400-700Mpa) and exposure time (1–15 minutes) against the inactivation of L. monocytogenes inoculated on Gorgonzola cheese slices and reported a remarkable resistance of L. monocytogenes up to 500MPa. The application of 400 MPa showed no effect for up to 15 minutes. The inactivation became evident at a pressure of 500 MPa for 5 minutes after which the barotolerance of L. monocytogenes decreased with increasing either the pressure or exposure time. Although there is no solid evidence of direct involvement of Hummus in food poisoning outbreaks in Jordan; reports from the JFDA implicate its involvement at least in three cases in 2014. The microbial analysis of Hummus samples from the first case revealed that samples contained Salmonella, B. cereus (1x10 4 cfu/g), coliform (1.2x10 5 cfu/g) and Escherichia coli (2x10 4 cfu/g) whereas samples analysis of another case showed high counts of coliform and E. faecalis (JFDA, 2014 un-published report). Outbreaks due to the consumption of contaminated Hummus were reported globally, with L. monocytogenes (Olimat et al. 2018), and Salmonella contamination in Tahini (Sokolowska et al. 2019). Recently, in 2023, the United States FDA reported several products containing Hummus with potential contamination of L. monocytogenes and 30,000 containers of hummus were recalled back (FDA, 2015). Moreover, Salmonella contaminated Hummus was linked to the one of the largest reported outbreaks in the US in 2007, which involved in 802 illnesses (CDC, 2010). Several outbreaks recorded between 2010 and 2021 in the US were also associated with hummus or Tahini contaminated with Salmonella , L. monocytogenes and E. coli resulted in 214 illnesses and 5 deaths (CDC, 2023). 4.3 Sensory evaluation of hummus The 9-point hedonic scale is widely used in measuring acceptability of food items. The sensory evaluation was carried out to assess the effect of HHP treatment as well as refrigerated storage for 52 weeks on the sensory quality of Hummus. Samples of G1 that showed high aerobic plate counts and spoilage symptoms were excluded from the second sensory evaluation session. Results of sensory analysis are shown in Table 3 . Evaluation of samples disclose no significant differences between the means of non-HHP treated (G1) samples, HHP treated (G2) samples at day 1, and HHP treated (G2) samples at week 52 of storage. No significant differences in Smoothness, texture, flavour, and colour, yet HHP treated samples showed a lower score than the non-HHP treated ones (G1) after 52 weeks of storage. Despite the observed decrease in overall acceptability, the differences remain statistically not significant. Table 3 Sensory evaluation of Hommos samples treated with HHP of 600 MPa for 6 minutes and stored bellow 5°C for a period of 52 weeks. Overall Smoothness Texture Flavour Colour G1 at day 1 7.39 a ± 0.97 7.39 a ± 0.84 7.35 a ± 0.90 7.35 a ± 0.95 7.79 a ± 0.89 G2 at day 1 7.35 a ± 0.95 7.43 a ± 0.98 7.41 a ± 1.03 7.33 a ± 1.01 7.63 a ± 1.01 G2 at week 52 7.18 a ± 0.95 7.16 a ± 0.96 7.16 a ± 0.87 7.04 a ± 0.87 7.49 a ± 0.96 ٭Each value is the mean of forty nine evaluation sheet, (n = 49). Means in the same column with different subscript are significantly different at the 5% level of probability ( P ≤ 0.05). Conclusion & Recommendation The HHP treatment of 600MPa for 6 minutes was able to achieve more than 5 log reductions of L. monocytogenes, S. enterica , and E. coli , and about 4 log reductions of natural microflora (APC and YM) in Hummus samples which extended the shelf life up to 52 weeks (1year) under refrigerated storage. This shelf-life extension is comparable to the shelf life of commercially sterilized Hummus despite the high-water activity that supports the growth of several microorganisms. Consequently, HHP in combination with refrigeration could be an effective non-thermal, preservative-free technique for fresh Hummus preservation. Declarations Conflict of interest: The authors declare that there is no conflict of interest in the preparation of this work. Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Ethics approval: Approval was obtained from the ethics committee of University of Jordan. The procedures used in this study adhere to the tenets of the Declaration of Helsinki. Informed consent was obtained from all individual participants included in the study. Author Contribution Shahein M.: Conception and design of the studyShahein M., Albawarshi Y., Kanaan, O.: Acquisition of dataShahein M., Al-khamaiseh A., Albawarshi Y., Eswed, B., Majdalawi, M., Kanaan, O.: Analysis and/or interpretation of dataShahein M., Al-khamaiseh A.: Drafting the manuscript: All authors: Revising the manuscript critically for important intellectual content. Acknowledgement The authors acknowledge Shaaban Hamada & Partners Company for in-kind support to this work; and Secure Vision Laboratory for donating the microbial strains. Data Availability The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. References Al-Holy, M., Al-Qadiri. H., Lin, M, and Rasco, B. (2006), Inhibition of Listeria innocua in Hummus by a combination of nisin and citric acid. Journal of Food Protection , 69 (6), 1322-1327. Al-Qadiri, H., Amr, A., Al-Holy, M. A., and Shahein, M. 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(2020), Effects of Water Activity ( aw ) on Microbial Stability as a Hurdle in Food Preservation, Ch 14 In Water Activity in Foods: Fundamentals and Applications , Edited by: Edited by: Barbosa-Cánovas, G., Fontana, A., Schmidt, SJ, and Labuza, T., John Wiley & Sons, Inc. The Food Processor SQL, 10.9.0 (2011). ESHA Research, Salem, Oregan, USA. United States Food and Drug Administration (FDA), 2015. Fresh Ideation Food Group LLC Recalls Sandwiches and Other Products Because of Possible Health Risk. https://www.fda.gov/safety/recalls-market-withdrawals-safety-alerts, Accessed date: April 2024. Usaga, J., Acosta, Ó., Churey, J., Padilla-Zakour, O. I. and Worobo, R. W. (2021), Evaluation of high-pressure processing (HHP) inactivation of Escherichia coli O157:H7, Salmonella enterica , and Listeria monocytogenes in acid and acidified juices and beverages. International Journal of Food Microbiology , 339: 109034. Yamani, M. I. and Isa, J. K. (2006), Microbiological Quality quality of Tehena and development of a generic HACCP plan for its production. World Journal of Agricultural Sciences , 2 (3): 290-297. Salazar, J., Natarajan, V., Stewart, D., Warren, J., Gonsalves, L., Mhetras, T., and Tortorello, M., (2019). Fate of Listeria monocytogenes in Ready-to-Eat Refrigerated Dips Treated with High Pressure Processing. Journal of Food Protection , 82 (8): 1320–1325. 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-4758410","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":341103459,"identity":"4e87fe8f-02ec-45a5-90c3-41709780b0f6","order_by":0,"name":"Mohammad Shahein","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEUlEQVRIiWNgGAWjYFACHjDJ2ABkMINY/BJgARD7AJFaJGeQrMXgBlwLdqDb3nvw080cO9kG/rMHPxdU2OQZ325+JsFQYZ3YwHgYqzVmZ84lS+duSzZukMhLlp5xJq3Y7M4xMwmGM+mJDQzHErBquZFjANTCnNggwWMgzdt2OHHbjQQzCUYgo4HhjAEOLca/c7fVJzbwnzH+zfvvf+LmGenfJBj/4dViBrQFpADI4G04kLhBIgdoSwMeLWfOmFnnbjtu3AZUac1zLDlxxp0zxRYJx9KN23D55XiP8e3cbdWy/UCH3eapsUvsn92+8caHGmvZfgnsIQYHbCg8kPFsEvh1YAP8DSRrGQWjYBSMgmEJAOOPZubmqL0rAAAAAElFTkSuQmCC","orcid":"","institution":"Zarqa University College, Al-Balqa Applied University","correspondingAuthor":true,"prefix":"","firstName":"Mohammad","middleName":"","lastName":"Shahein","suffix":""},{"id":341103462,"identity":"d5352cbc-1366-46aa-957d-9d28758cd1cc","order_by":1,"name":"Yanal Albawarshi","email":"","orcid":"","institution":"Zarqa University College, Al-Balqa Applied University","correspondingAuthor":false,"prefix":"","firstName":"Yanal","middleName":"","lastName":"Albawarshi","suffix":""},{"id":341103465,"identity":"d30a3e96-7256-4d88-a701-6fdb37e8f594","order_by":2,"name":"Ashraf Al-khamaiseh","email":"","orcid":"","institution":"Applied Science Private University","correspondingAuthor":false,"prefix":"","firstName":"Ashraf","middleName":"","lastName":"Al-khamaiseh","suffix":""},{"id":341103466,"identity":"f35c7416-1939-44b4-b7c5-5071d33cb296","order_by":3,"name":"Bassam El-Eswed","email":"","orcid":"","institution":"Zarqa University College, Al-Balqa Applied University","correspondingAuthor":false,"prefix":"","firstName":"Bassam","middleName":"","lastName":"El-Eswed","suffix":""},{"id":341103468,"identity":"5dd87578-74fb-4829-946c-94f60fd2accf","order_by":4,"name":"Omar Kanaan","email":"","orcid":"","institution":"Applied Science Private University","correspondingAuthor":false,"prefix":"","firstName":"Omar","middleName":"","lastName":"Kanaan","suffix":""},{"id":341103470,"identity":"e52e32a8-0b8d-4db8-8558-a4a9df520391","order_by":5,"name":"Majdi Majdalawi","email":"","orcid":"","institution":"Zarqa University College, Al-Balqa Applied University","correspondingAuthor":false,"prefix":"","firstName":"Majdi","middleName":"","lastName":"Majdalawi","suffix":""}],"badges":[],"createdAt":"2024-07-17 19:03:36","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4758410/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4758410/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":63028370,"identity":"6ddd4e68-e6ee-4273-b7cc-5f1fcb79948f","added_by":"auto","created_at":"2024-08-22 08:53:06","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":762466,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4758410/v1/420af76f-6a00-4483-81b6-9add6d2a15ca.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Non-thermal shelf-life extension of fresh Hummus by High Hydrostatic Pressure and refrigeration","fulltext":[{"header":"Industrial application","content":"\u003cul\u003e\n \u003cli\u003eHHP at 600 MPa for 6 minutes in combination with refrigeration \u0026le;5\u0026deg;C was able to achieve more than 5 logs reduction for certain pathogens associated with numerous Hummus outbreaks.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eThe combined treatment extended the shelf life for about 1 year (52 weeks) without using of chemical preservatives or post-filling heat treatment.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eThis hurdle combination would be an appropriate alternative for the industrial sector to the commercial sterilization of Hummus by heat treatment.\u003c/li\u003e\n\u003c/ul\u003e"},{"header":"Introduction","content":"\u003cp\u003eHummus, a ready to eat food, is produced by mixing finely ground cooked chickpeas (\u003cem\u003eCicer arietinum\u003c/em\u003e L) with sesame paste, salt and acidulant like fresh lemon juice or citric acid as the main ingredients, though, garlic, basil, paprika, red pepper, jalapeno, and olive oil are added to give variety of flavours.\u003c/p\u003e \u003cp\u003eThanks to its main components, considering the variation in recipes, the nutritional value of this vegetarian product is rich due to the high contents of protein (6\u0026ndash;10%) and unsaturated fat (8\u0026ndash;12%), and supplies 166 calories per 100 grams which makes it a cheap source of nutrients (The food processor, 2011). Hummus had attracted the consumers around the world in the recent decades despite it was originated in the Levant, and it has expanded in many European countries, United States and Canada (Al-Qadiri et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAs a ready-to- eat food, the microbial criteria of Hummus shall meet those set by the Jordanian Food and Drug Administration (JFDA, 2011). The microbial criteria stipulate that Aerobic Plate Count (APC) should not exceed 10\u003csup\u003e6\u003c/sup\u003e colony forming unit per gram (cfu/g), while \u003cem\u003eListeria monocytogenes\u003c/em\u003e, \u003cem\u003eSalmonella\u003c/em\u003e and \u003cem\u003eEscherichia coli\u003c/em\u003e O157:H7 shall not be detected in 25 grams sample for such foods to be classified as \u0026ldquo;High Quality\u0026rdquo;. The microbial load of Hummus is low due to its preparation method, in which the Chickpeas are boiled. Moreover, Tahini (sesame paste) which is the second main component is classified as a low-risk food due to its low water activity, and the effect of heat during roasting and grinding of sesame seeds. Tahihi still contains some viable microorganisms which could grow when water activity increased to suitable levels upon its incorporation in products having high moisture levels like Hummus (Yamani and Isa, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Therefore, the initial microbial quality of Hummus is directly influenced by its ingredients, preparation steps, storage conditions, display, and dispensing environment (Al-Holy, et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHummus is generally produced and consumed fresh at households and in restaurants with shelf life of few days under refrigeration (Karam, et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In the past few years, markets have had fresh Hummus packed in press-to-seal plastic containers kept under refrigeration with chemical preservatives having shelf life up to one month. The commercially- sterilized product packed in metal cans has been produced for many decades in which the product is subjected to high temperature for long time. Recently, the advanced packaging solutions allowed food industry to produce aseptically filled flexible containers in which the product is subjected to high heat treatment. Although this thermally- treated products has a shelf life of one to two years, its flavour, colour, nutritional and other organoleptic properties are somewhat inferior to the fresh product (Amr, et al.,2017). Consequently, there is a need to produce and preserve the product in such a way to render it not only safe but also to maintain its good nutritional, freshness, and sensory qualities without compromising its shelf life, especially with the increasing demand for fresher, preservatives free and minimally processed foods.\u003c/p\u003e \u003cp\u003eSeveral methods can satisfy this objective especially the non-thermal ones like high hydrostatic pressure, pulsed electrical field, refrigeration and irradiation or a combination of two or more methods (Shahein, et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Juneja, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2003\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHigh Hydrostatic pressure processing (HHP) is an emerging preservation technology that employs the pressures in the range of 100\u0026ndash;800 MPa with or without the application of heat, and it is usually applied to pre-packaged food items (Shahein, et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Usage, et al., 2021). The application of HHP in combination with one or more processing method such as refrigeration is growing and may expand significantly with the development of high-pressure system fabrication. Some research work was conducted to utilise HHP technology to ensure safety of ready to eat foods and to extend their shelf life.\u003c/p\u003e \u003cp\u003eSalazar et al. (\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) investigated the effect of 350MPa for exposure time of 4 minutes and found that \u003cem\u003eListeria monocytogenes\u003c/em\u003e count was reduced from 6.85 Log to 4.27 Log inducing only 2.58 Log reduction. Shahein et al., (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) studied the effects of HHP of 600 MPa from 1 to 6 minutes against \u003cem\u003eL. monocytogenes, Staphylococcus aureus\u003c/em\u003e and \u003cem\u003eE. coli\u003c/em\u003e in low salt white cheese to determine the D\u003csub\u003e600MPa\u003c/sub\u003eValue and revealed that \u003cem\u003eL. monocytogenes\u003c/em\u003e was not detected after 4 minutes of application while the, \u003cem\u003eS. aureus\u003c/em\u003e and \u003cem\u003eE. coli\u003c/em\u003e showed survivors of 2.69 and 2.26 log cfu/g after 6 minutes exposure which disclose the significance of longer exposure time specially against \u003cem\u003eS. aureus\u003c/em\u003e and \u003cem\u003eE. coli\u003c/em\u003e.\u003c/p\u003e \u003cp\u003eAccordingly, the objective of this work was to study the effect of the high hydrostatic pressure treatment of 600MPa for 6 minutes on several pathogens in fresh Hummus, and the possibility of extending the shelf life up to one year (52 weeks) under refrigerated storage.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Microbial strain preparation\u003c/h2\u003e \u003cp\u003eFreeze-dried cultures of \u003cem\u003eListeria monocytogenes\u003c/em\u003e (ATCC 13932), \u003cem\u003eSalmonella enterica\u003c/em\u003e (ATCC 13314), and \u003cem\u003eEscherichia coli\u003c/em\u003e O157:H7 (ATCC 43888) were donated from Secure Vision Laboratory (Amman, Jordan). Each strain freeze-dried bead was rehydrated in 9 mL Brain Heart Infusion \u0026ndash; BHI broth (bioMerieux, I\u0026rsquo;Etoile, France) and incubated for 24 h at 37\u0026deg;C, after which each culture was streaked onto appropriate selective agar and onto Tryptic Soy Agar \u0026ndash; TSA (Biokar Diagnostics, Beauvais, France). Selective medias used were Oxford agar (Oxoid, Hampshire, UK), XLD agar (bioMerieux, I\u0026rsquo;Etoile, France), and Malt extract agar (Merck KGaA, Darmstadt, Germany) for \u003cem\u003eL. monocytogenes\u003c/em\u003e, \u003cem\u003eS. enterica\u003c/em\u003e, \u003cem\u003eE. coli\u003c/em\u003e, respectively. After incubation for 48 h at 37\u0026deg;C the TSA plates were checked for purity while the selective media plates were used to check for typical morphological properties.\u003c/p\u003e \u003cp\u003eA single colony of each strain from TSA was inoculated into 9 mL BHI broth in Falcon tube and incubated at 37\u0026deg;C for 24 h. After incubation, each tube was vortexed and centrifuged at 5\u0026deg;C for 10 min at 6000 rpm High Speed Refrigerated Centrifuge (CFGR-18.5JP, Infitek, China). Aseptically, broth was decanted, and the sediment cells were re-suspended into phosphate-buffered saline \u0026ndash; PBS (pH 7.2) and centrifuged again. The washing procedure was carried out twice. Finally, the sediment pellet was re-suspended in 20 mL PBS to yield approximate inoculum of 10\u003csup\u003e8\u003c/sup\u003e cfu/mL. The inoculum was stored at 4\u0026deg;C and used within 24 h for Hummus sample inoculation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Hummus Sample Preparation\u003c/h2\u003e \u003cp\u003eA batch of 30 kg of Hummus was prepared according to a recipe used in a local restaurant. The recipe followed is consisted of dry chickpeas 6 kg, Tahini 6 kg, salt 0.24 kg, citric acid 0.210 kg, sodium bicarbonate 0.050 kg and water with ice cubes (around 12 kg) to complete the total weight of 30 kg. The raw materials were acquired from the restaurant and the preparation process was performed at their workshop.\u003c/p\u003e \u003cp\u003eDry chickpeas were sorted and cleaned manually then soaked in potable tap water (in ratio of 1:3) for 8 hours. After straining, the chickpeas were boiled in water with sodium bicarbonate for two hours until get soft. The boiled seeds were precooled with tap water, then spread in a shallow stainless-steel tray and cooled rapidly to 4\u0026deg;C within 90 minutes using an efficient refrigerator. In a high-speed mixer, the cooled seeds were pulverised to a smooth paste and mixed with the other ingredients of Tahini, salt, citric acid, and cold water with ice cubes that had been treated with reverse osmosis unit. The ready Hummus mix was divided into 5 portions of 6 kg, approximately, each for an individual microbial strain inoculation. Preparation process was fully controlled with good hygienic practices.\u003c/p\u003e \u003cp\u003ePortions 1 and 2 were not inoculated, while portions 3, 4, and 5 were inoculated separately with 9 mL of microbial strain broth of \u003cem\u003eL. monocytogenes\u003c/em\u003e, \u003cem\u003eS. enterica\u003c/em\u003e, \u003cem\u003eand E. coli\u003c/em\u003e, respectively, and homogenized (L5M-A, Silverson, USA) to reach a count of 10\u003csup\u003e5 \u0026minus;\u0026thinsp;1\u003c/sup\u003e0\u003csup\u003e6\u003c/sup\u003e cfu/g. After inoculation, each Hummus portion was packed in 60 laminated pouches (Ampac Flexibles, Wolverhampton, UK) with about 100 g each, and kept in an ice box at 0\u0026ndash;3\u0026deg;C until HHP treatment. Pouches were made of three layers of Polyethylene Tetra- phthalate, Aluminium foil, and Cast Poly Propylene with thicknesses of 12, 8 and 70 microns. Consequently, five groups (G) of samples were obtained; G 1 and 2 which contain the natural microflora; G3, G4 and G5 were inoculated with \u003cem\u003eL. monocytogenes\u003c/em\u003e, \u003cem\u003eS. enterica\u003c/em\u003e, \u003cem\u003eand E. coli\u003c/em\u003e, respectively.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e3.3 HHP treatment\u003c/h2\u003e \u003cp\u003eHigh hydrostatic pressure treatment was carried out at a commercial facility in Dubai (Smart Foods Solutions, Dubai, UAE) using a Hyperbaric 55 high pressure processing unit (Condado de Trevi\u0026ntilde;o, Burgos, Spain). Samples were retained refrigerated\u0026thinsp;\u0026lt;\u0026thinsp;5\u0026deg;C until the time of HHP treatment. All Hummus samples, except samples of the G1, were subjected to HHP at 600 MPa for pressure-holding time of 6 min. Water at 12.7 C was used as pressurising medium.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Microbial Count\u003c/h2\u003e \u003cp\u003eAerobic Plate Count (APC) and Yeast and Molds count (YM) were carried out for samples of G1 and G2, while samples of G3, 4 and 5 were investigated for the targeted inoculated pathogens. To determine the initial count, numeration was performed immediately before HHP treatment. While enumeration was carried out after the treatment immediately, at Zero time, and later every 4 weeks up to 52 weeks (1 year).\u003c/p\u003e \u003cp\u003eAs per ISO method 6887-1:1999, a quantity of 25\u0026thinsp;\u0026plusmn;\u0026thinsp;1 g thoroughly mixed sample was weighed and transferred aseptically to a dilution bottle containing nine-fold (225 mL) sterile buffered peptone water at ambient temperature to prepare initial suspension. Further decimal dilutions were prepared using 9 mL sterile peptone water at ambient temperature to the final dilution of 10\u003csup\u003e8\u003c/sup\u003e. APC, YM, count of \u003cem\u003eL. monocytogenes, S. enterica\u003c/em\u003e and \u003cem\u003eE. coli\u003c/em\u003e was conducted as per ISO methods 4833:1-2013, 21527-1:2008, 11290-2:2017, 6579-1:2017 and 16649-2:2001, respectively.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Chemical analysis\u003c/h2\u003e \u003cp\u003eMoisture, ash, ether extract (fat) and protein were determined following the methods with numbers 971.28, 942.05, 920.39, 983.14 of AOAC (2011), whereas Nitrogen free extract content (carbohydrates) was estimated mathematically by subtracting sum of protein, fat, ash, and moisture from 100.\u003c/p\u003e \u003cp\u003eTitratable acidity and pH were performed following method number 981.12, 942.15 of AOAC 2011). Water activity was measured using Novasina Thermoconstanter Model TH 200 (Novasina, Switzerland).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Sensory analysis of hummus\u003c/h2\u003e \u003cp\u003eSensorial quality evaluation of hummus samples was carried out as described by Lawless and Heymann (2010). A total of 20 (the same 20 panellists for each replicate) habitual hommos consumer panellists were asked to conduct the evaluation procedure with Scores assigned ranged from 1 to 9 indicating dislike extremely to like very much, respectively. Samples of G1 and G2 were included in the evaluation at the first session within 24 hours of HHP treatment, and only samples of G2 were evaluated at week 52.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Statistical analysis:\u003c/h2\u003e \u003cp\u003eStatistical analysis of data obtained in this study was performed using SAS statistical program (SASI, 2002). Analysis of Variance (ANOVA) was carried out using the General Liner Model procedure to elucidate the effect of HHP and refrigerated storage on the various quality attributes. Means were separated using Least Significant Difference test (LSD) to compare significance at 5% level of probability (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05). The experiments were conducted in duplicate.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and discussions","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.1 Chemical properties\u003c/h2\u003e \u003cp\u003eThe chemical properties of Hummus samples used in this work are depicted in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Hummus is considered a highly perishable ready-to-eat moist food due to its high water activity levels (0.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001) along with the availability of nutrients that support the growth of natural microflora which could affect product stability and its shelf life. Many foodborne pathogens could grow in such water activity (Osaili et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The minimum level of water activity for the growth of \u003cem\u003eL. monocytogenes, Salmonella\u003c/em\u003e, and \u003cem\u003eE. coli\u003c/em\u003e is 0.92, 0.94, and 0.95, respectively (Tapia et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Jay, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Fungi could grow in media with a water activity (aw) of 0.8 while many types of yeast could tolerate a level of 0.6 aw (Park, et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2014\u003c/span\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\u003eChemical properties of Hummus samples used in this work.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMoisture\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProtein\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEther extract\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNitrogen free extract\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAsh\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAcidity%\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eWater activity\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e66.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.38\u0026plusmn;\u003c/p\u003e \u003cp\u003e0.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.55\u0026thinsp;\u0026plusmn;\u0026thinsp;0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.85\u0026thinsp;\u0026plusmn;\u0026thinsp;0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.001\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\u003eEach value represents mean of two replicates (N\u0026thinsp;=\u0026thinsp;2)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD.\u003c/p\u003e \u003cp\u003eThe average pH value found in Hummus was 4.8 categorizes Hummus as a low-acid food. Low-acid foods (pH\u0026thinsp;\u0026ge;\u0026thinsp;4.6) could support the growth of various microorganisms including toxin-producing pathogens (ICMSF, 1980). Numerous aspects may affect pH including organic acid concentration, temperature, the initial pH of the food, and their buffering capacity which tends to maintain pH levels or arrest their decrease (Derossi, et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe total acid concentration contained within a food item (originally and added) could be measured by titratable acidity (or total acidity). The initial titratable acidity present in Hummus (0.85% as citric acid) is mainly due to the added citric acid. The added acid reduces the pH value enhances the organoleptic properties and improves its keeping quality, whereas developed acidity is unfavourable in such a product.\u003c/p\u003e \u003cp\u003eReduction in pH value to a certain level that does not impair the organoleptic characteristics could facilitate the preservation of food products. As the pH decreases, inhibitory effects against some microorganisms will occur depending on their minimum pH limit for growth. The reduction in pH could increase the proportion of un-dissociated forms of organic acids present in Hummus mainly citric acid, thus, the efficacy of organic acids as antimicrobial agents will increase (ICMSF, 1980). However, the pH value in Hummus samples used in this work is still insufficient to prevent microbial growth without the application of other hurdles.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.2 Microbial analysis\u003c/h2\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the microbial load of samples before and after HHP treatment. Samples of G1 and G2 contained the natural microflora present in Hummus during preparation, whereas the other groups contained inoculated strains. The APC of both G1 and G2 after preparation was 4.71 and 4.76 Logs, while the counts of YM were 3.69 and 3.77 Logs, respectively. APC and YM counts are considered reasonable in such a product since the ingredients are not sterile. Moreover, the product is subjected to several processing steps after boiling and cooling of chickpeas such as grinding and mixing which may increase the microbial load. Low numbers of APC and YM counts reflect the hygienic conditions adopted during the preparation steps and indicate that Hummus samples are complying with the microbial criteria of ready-to-eat foods issued by the Jordanian Food and Drug Administration (JFDA, 2011).\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\u003eMicrobial count of Hummus samples treated with HHP at 600 MPa for 6 minutes and stored bellow 5\u0026deg;C.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"15\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGroup #\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTarget\u003c/p\u003e \u003cp\u003eMicroorganism\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eInitial count\u003c/p\u003e \u003cp\u003eLog cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHHP treatment\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZero-time Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eWeek 4 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c8\" colspan=\"2\" namest=\"c7\"\u003e \u003cp\u003eWeek 8 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" nameend=\"c10\" namest=\"c9\"\u003e \u003cp\u003eWeek 12 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eWeek 42 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e \u003cp\u003eWeek 44 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" colname=\"c14\"\u003e \u003cp\u003eWeek 48 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e \u003cp\u003eWeek 52 Log cfu/g\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eG1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAPC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.71\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eNo Treatment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6.98\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.69\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e7.86\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eG2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAPC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.76\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e600MPa\u003c/p\u003e \u003cp\u003efor 6 minutes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e1.95\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e2.08\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e2.32\u003csup\u003eC\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.77\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eL. monocytogenes\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.49\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eS. enterica\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.61\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eE. Coli O157:H7\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.43\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c12\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c15\"\u003e \u003cp\u003eND\u003csup\u003eb\u003c/sup\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\u003eEach value represents the mean of two replicates (N\u0026thinsp;=\u0026thinsp;2)\u0026thinsp;\u0026plusmn;\u0026thinsp;SD.\u003c/p\u003e \u003cp\u003eMeans in the same row with different superscripts are significantly different at the 5% level of probability (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eSamples of Group 1 were not subjected to HHP treatment, yet they were stored under refrigeration. After 4 weeks of refrigerated storage, the APC and YM showed a significant increase to 6.98 and 7.86 Logs, respectively, which were deemed to be unfit for human consumption according to JFDA microbial criteria (JFDA, 2011). Moreover, spoilage symptoms appeared in the forms of gas holes, sourness, and a putrefactive smell.\u003c/p\u003e \u003cp\u003eConcerning G2 samples which contained the natural microflora of Hummus and were subjected to HHP treatment, the results of APC and YM showed a significant decline from 4.76 and 3.77, respectively, to less than 1 Log for both counts. Furthermore, samples were kept refrigerated for a period of 52 weeks and were monitored every 4 weeks against APC and YM. The first significant increase in APC of G2 was shown at week 44 with a count of 1.95 Log. Despite that increase in APC, the YM count remained unchanged till week 52 with less than 1 Log. It is worth noting that plate count\u0026thinsp;\u0026lt;\u0026thinsp;10 cfu g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was considered as \u0026ldquo;not detected\u0026rdquo; and treated statistically as zero.\u003c/p\u003e \u003cp\u003eOn the other hand, all pathogens inoculated samples of G3, G4, and G5 showed significant reductions to undetectable limits immediately after the HHP treatment. Moreover, samples of Groups 3, 4, and 5 were kept under refrigeration for a period of 52 weeks and tested against the inoculated pathogens every 4 weeks. None of the samples showed a detectable limit of any targeted pathogen, neither \u003cem\u003eL. monocytogenes, S. enterica nor E. coli.\u003c/em\u003e These results highlight the impact of HHP treatment of 600 MPa for 6 minutes on the targeted pathogens in Hummus samples of more than 5 logs reduction. Despite that, a sample of each Group (3, 4, and 5) at week 50 was sent to an ISO 17025 accredited external laboratory for microbial detection of the targeted inoculated pathogen as an additional procedure of verification of the results. The \u003cem\u003eL. monocytogenes\u003c/em\u003e showed\u0026thinsp;\u0026lt;\u0026thinsp;10 cfu.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, \u003cem\u003eE. coli\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;\u003cem\u003e0.3 MPN.\u003c/em\u003e g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e while \u003cem\u003eS. enterica\u003c/em\u003e was absent.\u003c/p\u003e \u003cp\u003eResults obtained in this work agree with Sokolowska et al. (2019) who reported more than 5 log reduction of \u003cem\u003eL. monocytogenes, Salmonella\u003c/em\u003e, and \u003cem\u003eE. coli\u003c/em\u003e using the HHP of 500MPa for 10 minutes. Another work conducted by Klog et al. (2018) showed somehow similar results in which the HHP at 550 MPs for 10 minutes induced a reduction in mesophilic, psychrophilic, and Enterobacteriaceae loads that allowed extending the shelf life of broccoli hummus up to 28 days under refrigeration. Alvarez et al. (2017) concluded that the counts of YM and lactic acid bacteria were not detected (less than 2 and 1 Log, respectively) after the HHP treatment of 600MPa for 15 and 25 minutes and remained undetected for a period of 60 days under refrigerated storage.\u003c/p\u003e \u003cp\u003eOn the other hand, Carminati et. al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2004\u003c/span\u003e) investigated the efficacy of various combinations of pressure (400-700Mpa) and exposure time (1\u0026ndash;15 minutes) against the inactivation of \u003cem\u003eL. monocytogenes\u003c/em\u003e inoculated on Gorgonzola cheese slices and reported a remarkable resistance of \u003cem\u003eL. monocytogenes\u003c/em\u003e up to 500MPa. The application of 400 MPa showed no effect for up to 15 minutes. The inactivation became evident at a pressure of 500 MPa for 5 minutes after which the barotolerance of \u003cem\u003eL. monocytogenes\u003c/em\u003e decreased with increasing either the pressure or exposure time.\u003c/p\u003e \u003cp\u003eAlthough there is no solid evidence of direct involvement of Hummus in food poisoning outbreaks in Jordan; reports from the JFDA implicate its involvement at least in three cases in 2014. The microbial analysis of Hummus samples from the first case revealed that samples contained \u003cem\u003eSalmonella, B. cereus\u003c/em\u003e (1x10\u003csup\u003e4\u003c/sup\u003e cfu/g), coliform (1.2x10\u003csup\u003e5\u003c/sup\u003e cfu/g) and \u003cem\u003eEscherichia coli\u003c/em\u003e (2x10\u003csup\u003e4\u003c/sup\u003e cfu/g) whereas samples analysis of another case showed high counts of coliform and \u003cem\u003eE. faecalis\u003c/em\u003e (JFDA, 2014 un-published report). Outbreaks due to the consumption of contaminated Hummus were reported globally, with \u003cem\u003eL. monocytogenes\u003c/em\u003e (Olimat et al. 2018), and \u003cem\u003eSalmonella\u003c/em\u003e contamination in Tahini (Sokolowska et al. 2019). Recently, in 2023, the United States FDA reported several products containing Hummus with potential contamination of \u003cem\u003eL. monocytogenes\u003c/em\u003e and 30,000 containers of hummus were recalled back (FDA, 2015). Moreover, \u003cem\u003eSalmonella\u003c/em\u003e contaminated Hummus was linked to the one of the largest reported outbreaks in the US in 2007, which involved in 802 illnesses (CDC, 2010). Several outbreaks recorded between 2010 and 2021 in the US were also associated with hummus or Tahini contaminated with \u003cem\u003eSalmonella\u003c/em\u003e, \u003cem\u003eL. monocytogenes and E. coli\u003c/em\u003e resulted in 214 illnesses and 5 deaths (CDC, 2023).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e4.3 Sensory evaluation of hummus\u003c/h2\u003e \u003cp\u003eThe 9-point hedonic scale is widely used in measuring acceptability of food items. The sensory evaluation was carried out to assess the effect of HHP treatment as well as refrigerated storage for 52 weeks on the sensory quality of Hummus. Samples of G1 that showed high aerobic plate counts and spoilage symptoms were excluded from the second sensory evaluation session.\u003c/p\u003e \u003cp\u003eResults of sensory analysis are shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Evaluation of samples disclose no significant differences between the means of non-HHP treated (G1) samples, HHP treated (G2) samples at day 1, and HHP treated (G2) samples at week 52 of storage. No significant differences in Smoothness, texture, flavour, and colour, yet HHP treated samples showed a lower score than the non-HHP treated ones (G1) after 52 weeks of storage. Despite the observed decrease in overall acceptability, the differences remain statistically not significant.\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\u003eSensory evaluation of Hommos samples treated with HHP of 600 MPa for 6 minutes and stored bellow 5\u0026deg;C for a period of 52 weeks.\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=\"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 \u003cdiv align=\"left\" 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\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSmoothness\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eTexture\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFlavour\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eColour\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG1 at day 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.39\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.39 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.35 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.35 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e7.79 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.89\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG2 at day 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.35\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.43 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.41 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;1.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.33 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;1.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e7.63 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;1.01\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eG2 at week 52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.18\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.16 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.16 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.04 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\" colspan=\"2\"\u003e \u003cp\u003e7.49 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e\u0026plusmn;\u0026thinsp;0.96\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\u003e٭Each value is the mean of forty nine evaluation sheet, (n\u0026thinsp;=\u0026thinsp;49).\u003c/p\u003e \u003cp\u003eMeans in the same column with different subscript are significantly different at the 5% level of probability (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026le;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion \u0026 Recommendation","content":"\u003cp\u003eThe HHP treatment of 600MPa for 6 minutes was able to achieve more than 5 log reductions of \u003cem\u003eL. monocytogenes, S. enterica\u003c/em\u003e, and \u003cem\u003eE. coli\u003c/em\u003e, and about 4 log reductions of natural microflora (APC and YM) in Hummus samples which extended the shelf life up to 52 weeks (1year) under refrigerated storage. This shelf-life extension is comparable to the shelf life of commercially sterilized Hummus despite the high-water activity that supports the growth of several microorganisms. Consequently, HHP in combination with refrigeration could be an effective non-thermal, preservative-free technique for fresh Hummus preservation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eConflict of interest: The authors declare that there is no conflict of interest in the preparation of this work.\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthics approval:\u003c/strong\u003e \u003cp\u003eApproval was obtained from the ethics committee of University of Jordan. The procedures used in this study adhere to the tenets of the Declaration of Helsinki. Informed consent was obtained from all individual participants included in the study.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eShahein M.: Conception and design of the studyShahein M., Albawarshi Y., Kanaan, O.: Acquisition of dataShahein M., Al-khamaiseh A., Albawarshi Y., Eswed, B., Majdalawi, M., Kanaan, O.: Analysis and/or interpretation of dataShahein M., Al-khamaiseh A.: Drafting the manuscript: All authors: Revising the manuscript critically for important intellectual content.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors acknowledge Shaaban Hamada \u0026amp; Partners Company for in-kind support to this work; and Secure Vision Laboratory for donating the microbial strains.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAl-Holy, M., Al-Qadiri. 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Fate of Listeria monocytogenes in Ready-to-Eat Refrigerated Dips Treated with High Pressure Processing. \u003cstrong\u003eJournal of Food Protection\u003c/strong\u003e, 82 (8): 1320\u0026ndash;1325.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-food","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"discoverfood","sideBox":"Learn more about [Discover Food](https://www.springer.com/44187)","snPcode":"","submissionUrl":"","title":"Discover Food","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"High hydrostatic pressure, non-thermal preservation, ready-to-eat, minimally processed, shelf life, Hummus","lastPublishedDoi":"10.21203/rs.3.rs-4758410/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4758410/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eConsumers are interested in fresher and minimally processed ready to eat foods, therefore this work aimed to investigate the efficacy of the of HHP of 600MPa for 6 minutes against \u003cem\u003eListeria monocytogenes\u003c/em\u003e, \u003cem\u003eSalmonella enterica\u003c/em\u003e, and \u003cem\u003eEscherichia coli\u003c/em\u003e O157:H7 in fresh hummus samples, and to study the significance of the combined treatment of HHP and refrigeration on the shelf life of Hummus samples. Results showed that a treatment of HHP at 600MPa for 6 minutes was able to achieve more than 5 log reductions of the tested pathogens, and about 4 logs for aerobic plate count (APC) and Yeast and Mold (YM), respectively. Moreover, pathogens remained undetectable during the period of refrigerated storage for 1 year, while APC and YM were increased to log 2.32 and \u0026lt;1 log, respectively. After 52 weeks of refrigerated storage, HHP treated samples showed no significant differences in respect to sensorial properties of hummus samples and remained microbiologically within the “High quality” standards according to the microbiological criteria of ready to eat foods.\u003c/p\u003e","manuscriptTitle":"Non-thermal shelf-life extension of fresh Hummus by High Hydrostatic Pressure and refrigeration","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-22 08:44:59","doi":"10.21203/rs.3.rs-4758410/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2024-08-16T11:59:31+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-14T17:27:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"74577785665296785201234356457933689525","date":"2024-08-14T13:30:54+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6385343468311879719695822781294368961","date":"2024-08-10T07:07:10+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-08T07:52:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-07T20:23:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"323845154951814796954125446367491416162","date":"2024-08-06T18:26:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"161056027441410779370528046775811015635","date":"2024-08-03T06:31:35+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-01T16:54:14+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-29T06:33:13+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-26T09:15:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Food","date":"2024-07-17T19:02:08+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-food","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"discoverfood","sideBox":"Learn more about [Discover Food](https://www.springer.com/44187)","snPcode":"","submissionUrl":"","title":"Discover Food","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"7867f52c-d2bb-4b5b-abc9-e3ce92da3167","owner":[],"postedDate":"August 22nd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-03-18T11:38:08+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-22 08:44:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4758410","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4758410","identity":"rs-4758410","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}