The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons

The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons | 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 The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons Ketty Suketi, Abdullah Bin Arif, Nidya Putri Zulia Kusuma Wardani, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6967879/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 Melon ( Cucumis melo L. var. Cantaloupe) is a climacteric fruit susceptible to postharvest damage. Early fruit harvesting can increase the shelf life of melon fruit, but early harvested fruit has low sugar content, and the color of the fruit flesh is less attractive. This study evaluated the effects of exogenous ethylene and its application time in increasing the sugar content and quality of early harvested melon during storage. Melon fruit was treated without exogenous ethylene application (control) and exogenous ethylene application (Ethrel) at a concentration of 100 ppm with application times of 0, 3, 6, and 9 (d0, d3, d6, and d9) days after harvesting (DAH). In the exogenous ethylene application, melon fruit was soaked in an exogenous ethylene solution for 1 minute and dried in air. Furthermore, melons were stored in an ambient room (28 ± 1 ◦C and 80 ± 5% RH) for 21 days. The results showed that 100 ppm ethylene treatment at 6 DAH (d6) accelerated the increase in sugar content (sucrose, fructose, and glucose) and color degradation in melon flesh. The d6 treatment also maintained the titratable acidity (TA) and vitamin C content. In addition, the shelf life of melons in the d6 treatment reached 12 days of storage. Therefore, exogenous ethylene treatment of 100 ppm at 6 DAH can be considered an appropriate treatment to improve the sugar content and quality of early harvested melons. Fructose Glucose Physiology Storage Sucrose Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Melon ( Cucumis melo L.) is an agricultural commodity of high economic value and ranks fifth among the most important fruits worldwide [ 1 ]. Among the different types of melon, cantaloupe is the most popular among consumers [ 2 ]. Andrade et al. [ 3 ] describe cantaloupe melon as having a netted skin with generally orange and thick flesh characterized by a fragrant aroma. Cantaloupe is classified as a climacteric fruit, making it susceptible to postharvest damage [ 4 ]. This damage can arise from various factors, including physiological, microbiological, chemical, and physical activities [ 5 ]. Common issues include bruising, rot, chilling injury, freezing injury, and surface shrinkage. These problems can occur both in the field and during distribution and storage, significantly reducing the fruit's commercial value. Without appropriate treatment, melons can deteriorate and rot approximately ten days after being stored in an ambient room [ 6 ]. Effective postharvest handling strategies for melon fruit are essential for superior quality and extended shelf life. Research by Wardani et al. [ 7 ] indicates that cantaloupe melons harvested early, specifically at 32 days after anthesis (DAA), 10 days earlier than the recommended harvest time, demonstrate a longer shelf life than fully ripe fruit. However, early-harvested melons often have lower quality, particularly regarding sugar content, as their carbohydrates are primarily starch (polysaccharides) [ 7 , 8 ]. Additionally, the flesh color of cantaloupe melons harvested early is paler than those harvested at full ripeness, making them less appealing to consumers [ 9 ]. Consumers prefer cantaloupe melons with attractive flesh color, appropriate moisture levels, sweetness, a crunchy texture, and pleasing aroma [ 10 ]. The primary sugars found in cantaloupe melons are sucrose (58.1%), fructose (25.6%), and glucose (17.5%), with total soluble solid (TSS) content ranging from 11 to 12 °Brix [ 11 , 12 ]. Therefore, it is necessary to implement strategies to enhance the postharvest quality of early-harvested cantaloupe melons. One effective technology for improving the postharvest quality of melon fruit is the application of ethylene. Ethylene is a plant hormone that accelerates fruit ripening. In climacteric fruits, ethylene ensures uniform ripeness and enhances fruit quality. Controlling ethylene production and exposure can significantly impact the ripening process. The application of ethylene in postharvest management can effectively regulate this process. Furthermore, the concentration of ethylene used is vital for achieving optimal fruit quality. Gao et al. [ 13 ] reported that the optimum ethylene concentration for postharvest treatment of melon fruit is 100 ppm. However, previous studies have not sufficiently considered the timing of ethylene application. Therefore, further research is necessary to explore how the timing of ethylene application affects the postharvest quality of early-harvest melons. The timing should be primarily evaluated based on the climacteric peak period of cantaloupe melons. Consequently, the main objective of this study is to identify the optimal timing for ethylene application to improve the postharvest quality of early-harvest cantaloupe melon. Material and Methods Plant Material Melon ( Cucumis melo L. var. Cantaloupe) was cultivated in a greenhouse in Jasinga, Bogor, Indonesia. The melons were harvested 32 days after anthesis, which is 10 days earlier than reported in previous studies. After harvesting, the fruits were taken to the laboratory at the Department of Agronomy and Horticulture, IPB University. Only undamaged melons of uniform size were selected for the study. The fruits were then rinsed with a sodium hypochlorite solution at 100 ml per liter. Subsequently, the melons were exposed to ethylene based on the assigned treatments and stored at room temperature (25–28°C). Each treatment group contained approximately 30 fruits, divided into three replications of 10 fruits each. Ethylene Treatments The type of ethylene used in this study was Ethrel 480 SL (C 2 H 6 ClO 3 P). The concentration of Ethrel used was 100 ppm [ 13 ]. Melon fruit was treated without exogenous ethylene application (control) and exogenous ethylene application (Ethrel) at a concentration of 100 ppm with application times of 0, 3, 6, and 9 (d0, d3, d6, and d9) days after harvesting (DAH), so there were five treatments. In the application of exogenous ethylene, melon fruit was soaked in exogenous ethylene solution for 1 minute and air-dried, then stored in a room at room temperature (25–28 o C). The treated fruit was then observed for 21 days after treatment. Measurements of Respiration Rate and Ethylene Productions Respiration rate and ethylene production were measured following the method suggested by Arif et al. [ 14 ]. The respiration rate and ethylene production in cantaloupe melons were measured using a Gas Analyzer (Merck Felix, type F-950) by flowing air in a sealed glass bottle into the Gas Analyzer with an airflow rate of 70 ml min − 1 (Felix's instrument). Measurements were performed by placing two whole melons in a closed 6 L jar for 60 minutes. The respiration rate was expressed as ml kg − 1 h − 1 , and ethylene production was expressed as ppm kg − 1 h − 1 . Measurements of Weight Loss and Softness The weight loss of the fruit was calculated using the method proposed by Arif et al. [ 14 ]. The percentage of weight loss was determined using the following formula: Weight loss (%) = ((Weight before storage - Weight after storage) / Weight before storage) x 100%. The results were expressed as a percentage (%). Fruit softness testing was conducted using the method described by Sun et al. [ 15 ]. A Stanhope-SETA penetrometer was employed with a total load of 152.5 g, which included a 102.5 g cone and a 50 g weight. The needle puncture, with a probe size of 2 mm, was applied for 10 seconds. Measurements were taken by inserting the penetrometer needle into the fruits base, middle, and tip. To calculate the softness, the penetration depth of the penetrometer needle was recorded, and the following formula was applied: r x 0.1 M x T, where r = average penetration depth value of the penetrometer needle; M = weight of the weight load; T = penetration time of the penetrometer needle (10 seconds). The softness was represented in mm g − 1 s − 1 . Measurements of Flesh Color The color were measured according to the method described by Arif et al. [ 14 ], with slight modifications. The color measurement was carried out in three different parts of the cantaloupe fruit (i.e., base, equatorial, and tip section) using the CR-400 Chroma Meter (Minolta Japan). The chromameter is calibrated with a white field. The color of cantaloupe rind and flesh were expressed L*, a*, b* and hue values. Then, the average was determined. Measurements of Total Soluble Solids (TSS) and Sugar Content The total soluble solids (TSS) were measured from triplicate extracts of melon cantaloupe juice using an Atago DR-A1 digital refractometer (Atago Co. Ltd., Tokyo, Japan) at a temperature of 28 ± 1°C, following the method suggested by Arif et al. [ 14 ]. The TSS results were expressed in degrees Brix (°Brix). To measure sugar contents (glucose, fructose, and sucrose), we followed the method described by Arif et al. [ 14 ]. A 5 g sample of melon was taken, and 20 ml of distilled water was added. The mixture was stirred with ultrasonics for 30 minutes and then filtered using a microfilter. The resulting supernatant was analyzed using a Dionex Ultimate 3000 high-performance liquid chromatograph (HPLC). The contents of glucose, fructose, and sucrose are expressed as percentages. Measurements of Titratable Acidity (TA) and Vitamin C Arif et al. [ 14 ] described the NaOH titration method for determining total acidity (TA) content. To measure TA, the extract is titrated with 0.1 N NaOH and expressed as a percentage of malic acid equivalents. The equivalent weight (EW) of the acid used in the TA calculation for melon fruit is based on malic acid, which has a value of 67. The formula for calculating the TA content of cantaloupe is as follows: Remarks: fp = Dilution factor EW = Equivalent weight (malic acid). The vitamin C content was evaluated using the method described by Ismillayli et al. [ 16 ]. First, the flesh of the cantaloupe melon was mashed to release the juice, which was then filtered through a cloth. A 10 g sample of the juice was measured and transferred into a 100 ml volumetric flask, where it was diluted with distilled water. From this solution, 10 ml was taken and placed in an Erlenmeyer flask. Three drops of starch solution were added as an indicator, and the mixture was titrated with iodine until a stable dark blue color was obtained. The iodine used as a titrant had a normality of 0.01 N. In the formula for calculating vitamin C, the equivalent weight (EW) refers to the predominant acid in vitamin C, which is ascorbic acid (Ismillayli et al. 2020). The equivalent weight of ascorbic acid is 0.88. Data Analysis Data were analyzed using a one-way analysis of variance (ANOVA) for each storage day. Significant differences among the treatment means were determined using the Duncan Multiple Range Test (DMRT) at a probability level of 5%. Statistical analyses were performed using SAS Portable Version 9.1.3, and the results are presented as the mean of three replications. Results and Discussion Respiration Rate and Ethylene Productions One of the key factors in determining the shelf life of fruit is its respiration rate and ethylene production. Ethylene is the primary hormonal trigger for the ripening of climacteric fruits, such as melons. In this process, there are both ethylene-dependent and ethylene-independent regulatory pathways that work together to manage ripening. Specific physiological processes during ripening are established as ethylene-dependent, while others function independently or are very sensitive to low levels of ethylene. For instance, in many fruits, including melons, ripening is marked by a temporary increase in respiration rates and an autocatalytic rise in ethylene production. Specific processes, such as climacteric respiration, stalk abscission zone formation, skin yellowing, and carotenoid content in Charentais-type Cantaloupe melon (cv. Védrantais) are dependent on ethylene [ 17 ]. Additionally, membrane damage and volatile compound synthesis are also partially influenced by ethylene [ 17 ]. In this study, the application of exogenous ethylene affected both the melons' respiration rate and ethylene production (Fig. 1). Cantaloupe melons treated with ethylene on days 0 and 3 of storage (d0 and d3) experienced a faster climacteric peak, occurring between days 3 and 6 of the storage period (Fig. 1A). They began to show signs of senescence from days 9 to 15. In contrast, those treated with ethylene on days 6 and 9 (d6 and d9) displayed a longer climacteric peak, lasting from days 6 to 12, with senescence starting on day 15 (Fig. 1A). Additionally, the rate of ethylene production followed a pattern similar to that of the respiration rate in melons during storage (Fig. 1B). Melon fruits treated with 100 ppm of exogenous ethylene tended to reach the climacteric peak earlier than the control. Furthermore, the ethylene production in melon fruit exposed to exogenous ethylene at the beginning of storage (from day 0 to day 6) was significantly higher. The d6 treatment maintained a low respiration rate and low ethylene production during the first six days of storage. This was because ethylene had not been applied to the melon fruit. However, after six days, both the respiration rate and ethylene production increased, which was expected to enhance the quality of the cantaloupe melons during storage. The rise in ethylene levels can stimulate positive physiological changes that improve the quality of the fruit without reducing its shelf life. By controlling ethylene levels, respiration can be reduced, starch degradation can be delayed, and the melons can develop more complex flavors while being less sweet, ultimately extending their shelf life [ 18 ]. Therefore, applying exogenous ethylene at 100 ppm on day six was deemed appropriate to slightly elevate ethylene production and respiration rates in postharvest cantaloupe melons during storage. Weight Loss and Softness Weight loss is one of the crucial factors related to fruit storage life because it can interfere with the visual appearance of the fruit [ 19 ]. Due to respiration and evaporation, melon fruit loses water. In addition, melon fruit undergoes a respiration process during storage, requiring energy obtained from the breakdown of starch, amino acids, pectin, and other compounds. Higher respiration rates and ethylene production increase weight loss [ 20 ]. In this study, weight loss in melon fruit increased with extended storage periods (Fig. 2A). Additionally, the weight loss observed in melons treated with d6 was lower than in the other treatments, with a reduction of 2–6% (Fig. 2A). The weight loss in cantaloupe melon was < 20%, which is relatively low. The weight loss observed in melons in the d6 treatment was lower than in other treatments, with a reduction of 2–6% (Fig. 2A). The addition of exogenous ethylene can accelerate the decomposition of cell wall membranes. Covalently bound pectin encourages an increase in water-soluble pectin, accelerates the degradation of hemicellulose and cellulose, and accelerates the decomposition of pectin bond ions so that the fruit becomes softer and higher weight loss [ 21 ]. As one of the basic parameters of postharvest quality, fruit softness affects shelf life and consumer acceptance. Ethylene plays an important role in fruit softening and firmness by activating cell wall-degrading enzymes, such as polygalacturonase, which hydrolyzes pectin in the cell wall, producing fruit softening. The higher in fruit softening during storage occurs because melon fruit is stimulated by ethylene during storage, so softening can increase with increasing ethylene concentration [ 22 ]. In this study, cantaloupe melon fruit softness increased during storage for all treatments (Fig. 2B).The softness of cantaloupe melon increased during storage for all treatments (Fig. 2B). The fruit treated with exogenous ethylene of 100 ppm at day 0 (d0) showed a faster softness increase than the other treatment (Fig. 2B). Conversely, the slowest increase in softness occurred for fruit treated with exogenous ethylene at 6 and 9 days into the storage period (treatments d6 and d9) (Fig. 2B). In the treatment of exogenous ethylene application of 100 ppm, the slowest increase in softness occurred in the fruit applied with exogenous ethylene on the sixth and ninth days of the storage period (treatments d6 and d9) (Fig. 2B). Therefore, exogenous ethylene treatment on day 6 can be considered to smaller weight loss and maintain the firmness of melon flesh with better quality. Flesh Color The lightness of melon flesh decreased over the storage period (Fig. 3A). Additionally, applying 100 ppm ethylene resulted in a faster decrease in lightness compared to the control. The treatment applied on day 6 (d6) exhibited a slower decrease in lightness than the 100 ppm ethylene application at other application times during storage (Fig. 3A). In contrast, the melon flesh's redness (a*) value increased during storage (Fig. 3B). Specifically, the redness (a*) values for treatments d0, d3, and d6 showed significant increases at 7 days of storage compared to the control and d9 (Fig. 3B). Therefore, the 100 ppm ethylene treatment influenced the color of the melon flesh, making it appear more orange or red. At 7 days of storage, the b* value was most pronounced in the 100 ppm ethylene treatment across all application times, with increases ranging from 12.97 to 20.78 (Fig. 3C). Moreover, the hue value of the melon flesh exhibited a consistent downward trend throughout the storage period (Fig. 3D). The control treatment maintained a higher hue value than those subjected to exogenous ethylene application. Notably, the reduction in hue value for the d6 treatment was substantial, with a decrease of up to 8.89 (Fig. 3D). Fruit color is a key factor that influences consumer choice. During the ripening process, the pigmentation of the fruit's flesh and rind determines its color [ 23 ]. As fruit is stored for longer periods, its hue value decreases. In this study, the d6 treatment demonstrated the smallest decrease in hue value in melon flesh compared to other treatments. The addition of exogenous ethylene affected the hue of cantaloupe melon flesh. This study's most effective concentration for reducing hue was 100 ppm, applied on the sixth day of the storage period. This treatment resulted in a color change of the fruit flesh from yellow to orange. It is hypothesized that applying exogenous ethylene on the sixth day is optimal because the melon fruit is expected to reach its climacteric peak by that time. According to Wardani et al. [ 7 ], early-harvested cantaloupe melons typically reach their climacteric peak on the eighth day after harvest. The yellowish color change in the flesh of climacteric fruits during storage is significantly influenced by both the ethylene produced by the fruit itself and the additional exogenous ethylene. Paul et al. [ 24 ] noted that adding exogenous ethylene to cantaloupe melons can accelerate the degradation of the fruit flesh, increase internal ethylene production, and hasten ripening. In this study, we observed that the lightness value of melon flesh (L*) decreased during storage. This decrease in L* indicates that the fruit is ripening, as the color of ripe flesh generally becomes deeper. This finding aligns with the research by Vanoli et al. [ 25 ], which demonstrated a decrease in the L* value as fruit ripeness increased. Additionally, Kasim and Kasim [ 26 ] noted that the decline in the L* value after several days of storage is attributed to changes in the color of the melon flesh, which transitions from bright green to yellow-orange. Therefore, treating cantaloupe melon fruit with 100 ppm of ethylene on day 6 (the d6 treatment) is recommended to enhance color characteristics during storage. Total Soluble Solids (TSS) and Sugar Content The total soluble solids (TSS) of cantaloupe melon fruit increased during storage, as shown in Fig. 4A. The most significant increase in TSS levels occurred in the d6 treatment after 14 days of storage, where the TSS value was 2.34 °Brix higher than the control. Additionally, on the seventh day of storage, there was no significant difference in TSS content between the d9 treatment and the control (Fig. 4A). The sucrose content of cantaloupe melon fruit also increased following ethylene application during storage (Fig. 4B). In the d6 treatment, the sucrose content was higher than in the other treatments. Furthermore, on the seventh day, the cantaloupe melon fruit treated with d6 rapidly increased sucrose content, 12-fold higher than the control. The melon fruit's fructose and sucrose content increased during storage (Figs. 4C and 4D). Finally, in the d6 treatment, the levels of fructose and glucose in the melon fruit were higher compared to the other treatments. Climacteric melons are classified as fruits that can continue their ripening process even after being harvested but cannot increase their TSS content if not treated to induce it [ 27 ]. Climacteric melons, including cantaloupe melons, can higher their TSS content due to exogenous ethylene. TSS is an important indicator of fruit quality and consumer acceptance [ 14 ]. In this study, TSS and total sugar in cantaloupe melons increased during storage (Fig. 5). In addition, the TSS, sucrose, fructose, and glucose content of melons in the d6 treatment showed higher values than the other treatments. This increase can presumably occur because exogenous ethylene applied at the beginning of storage can process starch into sugar earlier, so the accumulation of soluble solids occurs faster. After reaching the highest TSS peak, cantaloupe melons experienced a decrease in TSS. Based on research by Lucchetta et al. [ 28 ], the reduction in TSS in cantaloupe melon fruit at the end of storage occurred because the fruit used sugar to help aerobic respiration and senescence process activity. The primary components of the soluble sugar fraction in ripe melon fruit are sucrose, glucose, and fructose. At harvest time, cantaloupe melons have a sugar content ranging from 23.23 to 61.40 mg/g [ 12 ]. Other climacteric fruits, such as tomatoes, show an increase in total sugar content of 1.5% when transitioning from the green to red ripeness phase [ 29 ]. During storage, mango fruit can experience an increase in total sugar of up to 28.55% [ 30 ]. This increase in total sugars is influenced by ethylene, which plays a significant role in ripening. According to Gao et al. [ 13 ], exogenous ethylene can enhance the sucrose content in fruit. In this study, the sucrose content of melon fruit in the d6 treatment reached 2.17%, which is 12 times higher than the sucrose content in the control group. Introducing ethylene and applying it to the fruit approaching the climacteric peak (after 6 days of storage) can boost the production of both endogenous sucrose and ethylene. Gao et al. [ 13 ] noted that the increase in sucrose content is associated with the expression of the CmSPS1, CmACO1, and CmMYB44 genes, which are activated by the regulatory activities of the sucrose synthase (SS) and sucrose phosphate synthase (SPS) enzymes. Moreover, Braun et al. [ 31 ] stated that sucrose serves as a source of metabolism for constructing carbon and energy frameworks that support plant growth and development, and plays a crucial role in enhancing the taste quality of melon fruit. Daryono and Genesiska [ 32 ] emphasized that sucrose accumulation contributes to taste quality by increasing the total sugar content in the fruit. In this study, melon fruit's fructose and sucrose content increased during storage. Generally, fructose accumulation was less than that of sucrose during the growth process and either decreased or remained unchanged during ripening. The average sucrose content in the mesocarp tissue was 58.1%, which was consistently higher than the glucose content at 17.5% and the fructose content at 25.6% [ 11 ]. This trend occurs because fructose accumulation happens at the beginning of fruit development, when the fruit is still unripe, and is subsequently converted into sucrose. As a result, sucrose becomes the dominant sugar in ripe fruit [ 33 ]. The increase in glucose content during the storage of cantaloupe melon was not as pronounced as the increase in sucrose content. The increase in glucose in cantaloupe melon is dependent on its sucrose content. Furthermore, exogenous ethylene application can enhance sucrose content and boost glucose and fructose levels. According to Yu et al. [ 34 ], in strawberries, the enzyme β-fructofuranosidase catalyzes the breakdown of sucrose into fructose and glucose within fruit cells. The availability of glucose in the metabolic process activates the enzyme phosphoglucomutase, which can be stimulated by ethylene treatment. Phosphoglucomutase is responsible for converting UDP-glucose into glucose-6-phosphate via α-D-glucose-1-phosphate, resulting in the production of glucose. Titratable Acidity (TA) and Vitamin C Titratable acidity (TA) and vitamin C are essential indicators of fruit quality. As illustrated in Fig. 5, both TA and vitamin C contents in melon fruits generally decreased during storage for all treatments. Specifically, the melon fruits in treatment d6 exhibited the lowest TA content compared to the other treatments throughout the storage period (Fig. 5A). Conversely, the melon fruits in the d6 treatment demonstrated higher vitamin C content than the other treatments during storages (Fig. 5B). Titratable acidity (TA) and vitamin C are important indicators of fruit quality. In this study, we observed that the TA and vitamin C content in melon fruits decreased during storage. Specifically, melon fruits in the treatment labeled d6 exhibited the lowest TA content compared to the other treatments throughout the storage period (Fig. 5A). This suggests that, during storage, melon fruits are still undergoing respiration, where the TA content is inversely related to sugar content. The increased ethylene production in the cantaloupe melon fruits from treatment d6 is expected to enhance sugar content while slightly lowering TA during ripening. During respiration, organic acids are converted into sugars, and their derivatives or utilization during storage can cause a reduction in TA [ 14 ]. TA tends to increase during the early stages of ripening and decrease towards the end [ 35 ]. Moreover, Cocco et al. [ 22 ] reported that applying exogenous ethylene can lower TA in climacteric fruits, speeding up the ripening process and promoting the accumulation of moisture and sugars. In addition to TA, vitamin C is a vital nutrient prone to oxidation during storage [ 14 ]. In this study, the melon fruits subjected to treatment d6 showed higher vitamin C content, which was maintained during storage (Fig. 5B). Therefore, the d6 treatment effectively preserved vitamin C content in postharvest cantaloupe melons. Conclusion Exogenous ethylene treatment at a concentration of 100 ppm applied 6 days after harvesting (d6) significantly enhances the quality and shelf life of early-harvested cantaloupe melons. This study demonstrates that the 100 ppm ethylene treatment at d6 accelerated the increase in sugar content (sucrose, fructose, and glucose) and resulted in color degradation in the melon flesh. Additionally, by the seventh day of storage, the sucrose content in the d6 treatment group was 1-1.8% higher compared to the other treatment. The d6 treatment also increased the edible portion of the melons while maintaining titratable acidity (TA) and vitamin C content. Furthermore, the shelf life of melons treated at d6 extended to 12 days of storage. Thus, applying exogenous ethylene at a concentration of 100 ppm at d6 is an effective method to improve the sugar content and overall quality of early-harvested melons. Declarations Conflict of Interest The Authors declare that there are no conflicts of interest. Author Contribution Conceptualization: KS, ABA, SS. Methodology: KS, ABA, NPZKW, SS, DPH, data curation: ABA, NPZKW, DPH, SMW, SP, W. Investigation: KS, ABA, NPZKW, SP. Visualization: KS, ABA, NPZKW, SMW, SP, W. Writing – original draft: KS, ABA, NPZKW, SS, DPH, S. Writing – review & editing: KS, ANA, NPZKW, SS, S. 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Frontiers in Plant Sci, 1-19. https://doi.org/10.3389/fpls.2024.1475496 Ribeiro BS, de Freitas ST (2020) Maturity stage at harvest and storage temperature to maintain postharvest quality of acerola fruit. Sci Hortic 260:1-11. https://doi.org/10.1016/j.scienta.2019.108901 Kowitcharoen L, Wongs-Aree C, Setha S, et al (2018) Pre-harvest drought stress treatment improves antioxidant activity and sugar accumulation of sugar apple at harvest and during storage. Agric Nat Res 52: 146 – 154. https://doi.org/10.1016/j.anres.2018.06.003 Wang H, Cui J, Bao R, et al (2024) Research progress on the effects of postharvest storage methods on melon quality. PeerJ 12(8):1–22. https://doi.org/10.7717/peerj.17800 Cocco C, Silvestre WP, Schildt GW, et al (2022) Effect of ethrel application on fruit quality at harvest and post-harvest storage of japanese plum ( Prunus salicina ) cv . Fortune . Braz Arch Biol Technol 65: 1–11. https://doi.org/10.1590/1678-4324-2022210183 Penchaiya P, Tijskens LMM, Uthairatanakij A, et al (2020) Modelling quality and maturity of ‘Namdokmai Sithong’ mango and their variation during storage. Postharvest Biol Technol 159:1-11. https://doi.org/10.1016/j.postharvbio.2019.111000 Paul V, Pandey R, Srivastava GC (2012) The fading distinctions between classical patterns of ripening in climacteric and non-climacteric fruit and the ubiquity of ethylene-An overview. J Food Sci Technol 49(1): 1–21. https://doi.org/10.1007/s13197-011-0293-4 Vanoli M, Cortellino G, Picchi V, et al (2023) Non­destructive determination of ripening in melon fruit using time­resolved spectroscopy. Adv Hortic Sci 37(1):75–82. https://doi.org/10.36253/ahsc-13943 Kasim R, Kasim MU (2014). Biochemical and color changes of fresh-cut melon (Cucumis melo L. cv. Galia) treated with UV-C. Food Sci Technol (Campinas) 34(3):547–551. https://doi.org/10.1590/1678-457x.6398 Kader AA (1999) Fruit maturity, ripening, and quality relationships. Acta Hortic 485: 203-208. Lucchetta L, Rombaldi CV, Silva JA, et al (2014) The effect of ethylene on transgenic melon ripening and fruit quality. Afric J Biotechnol 13(32):3252-3261. https://doi.org/10.5897/AJB2013.13218 Sammi S, Masud T (2007) Effect of different packaging systems on storage life and quality of tomato ( Lycopersicon esculentum var. Rio Grande ) during different ripening stages. J Food Safety 9: 37-44. Lamba AK, Kumar S, Prakash S. (2020). Effect of pre-harvest application of chemicals and pesticide on fruit ripening in mango ( Mangifera indica L.) under ambient conditions. J Pharmac Phytochem 10(2):883–886. Braun DM, Wang L, Ruan YL (2014) Understanding and manipulating sucrose phloem loading, unloading, metabolism, and signalling to enhance crop yield and food security. J Exp Bot, 65(7):1713–1735. https://doi.org/10.1093/jxb/ert416 Daryono BS, Genesiska (2012) Pewarisan karakter fenotipik buah melon (Cucumis melo L.) kultivar gama melon basket hasil teknik seleksi buah. J Ilmu Pengetahuan dan Teknol Tepat Guna 2:9–18. Villanueva MJ, Tenorio MD, Esteban MA, et al (2004) Compositional changes during ripening of two cultivars of muskmelon fruit. Food Chem 87(2):179–185. https://doi.org/10.1016/j.foodchem.2003.11.009 Yu JQ, Li ZT, Chen S, et al (2024) Analysis of ethylene signal regulating sucrose metabolism in strawberry fruits based on RNA-seq fruit kept at ambient conditions. Food Chem 405:134908 . https://doi.org/10.1016/j.foodchem .2022.134908. Gebregziabher AA, Supriyadi S, Indarti S, et al (2021). Texture profile and pectinase activity in tomato fruit ( Solanum lycopersicum , servo f1) at different maturity stages and storage temperatures . J Agro Sci 9(1):20-34. 10.18196/pt.v9i1.9139. 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-6967879","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":478564744,"identity":"01c139b2-0086-49da-a29b-e19c83bcc48c","order_by":0,"name":"Ketty Suketi","email":"","orcid":"","institution":"IPB University (Bogor Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Ketty","middleName":"","lastName":"Suketi","suffix":""},{"id":478564745,"identity":"1be7007b-5e5d-487c-87e4-cf6fc53567ad","order_by":1,"name":"Abdullah Bin Arif","email":"data:image/png;base64,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","orcid":"","institution":"National Research and Innovation Agency","correspondingAuthor":true,"prefix":"","firstName":"Abdullah","middleName":"Bin","lastName":"Arif","suffix":""},{"id":478564747,"identity":"d9997a4a-406c-4beb-8879-9b8cba50741d","order_by":2,"name":"Nidya Putri Zulia Kusuma Wardani","email":"","orcid":"","institution":"IPB University (Bogor Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Nidya","middleName":"Putri Zulia Kusuma","lastName":"Wardani","suffix":""},{"id":478564749,"identity":"5b71a85b-d338-4d0d-9dac-2955c6c91498","order_by":3,"name":"Slamet Susanto","email":"","orcid":"","institution":"IPB University (Bogor Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Slamet","middleName":"","lastName":"Susanto","suffix":""},{"id":478564750,"identity":"e967718a-996f-4d25-8ba9-8112053c5e26","order_by":4,"name":"Dhika Prita Hapsari","email":"","orcid":"","institution":"IPB University (Bogor Agricultural University","correspondingAuthor":false,"prefix":"","firstName":"Dhika","middleName":"Prita","lastName":"Hapsari","suffix":""},{"id":478564751,"identity":"1a6dc21c-88bf-4236-ba21-428a5da41fdd","order_by":5,"name":"Siti Mariana Widayanti","email":"","orcid":"","institution":"National Research and Innovation Agency","correspondingAuthor":false,"prefix":"","firstName":"Siti","middleName":"Mariana","lastName":"Widayanti","suffix":""},{"id":478564752,"identity":"f4f35126-6359-4cbc-9db1-d63a9dad39ac","order_by":6,"name":"Sulusi Prabawati","email":"","orcid":"","institution":"National Research and Innovation Agency","correspondingAuthor":false,"prefix":"","firstName":"Sulusi","middleName":"","lastName":"Prabawati","suffix":""},{"id":478564753,"identity":"029bfeff-ef05-4909-841e-8d60ba9d8e45","order_by":7,"name":"Waryat Waryat","email":"","orcid":"","institution":"National Research and Innovation Agency","correspondingAuthor":false,"prefix":"","firstName":"Waryat","middleName":"","lastName":"Waryat","suffix":""},{"id":478564754,"identity":"5751deb8-bb02-4add-986e-5c4fab76bbec","order_by":8,"name":"Setyadjit Setyadjit","email":"","orcid":"","institution":"National Research and Innovation Agency","correspondingAuthor":false,"prefix":"","firstName":"Setyadjit","middleName":"","lastName":"Setyadjit","suffix":""}],"badges":[],"createdAt":"2025-06-24 16:53:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6967879/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6967879/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85862274,"identity":"deafb63a-1e5e-439c-9727-fb0f4f73778e","added_by":"auto","created_at":"2025-07-02 12:29:40","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":41535,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in respiration rate (A) and ethylene production (B) in cantaloupe during the storage period. Data are means of three replicates. Different letters in the same day indicate significant difference by the Duncan multiple range test (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/1d7af91bc1b076fb8c7e3ef9.jpg"},{"id":85861250,"identity":"80ebd33c-0ee5-4276-996c-1114e47d4743","added_by":"auto","created_at":"2025-07-02 12:21:40","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":34651,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in weight loss (A) and softness (B) in cantaloupe during the storage period. Data are means of three replicates. Different letters in the same day indicate significant difference by the Duncan multiple range test (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/9c442114fd2168346fc595b0.jpg"},{"id":85861253,"identity":"1eb605b1-7f2d-4342-8ade-fb9bc12dfba9","added_by":"auto","created_at":"2025-07-02 12:21:40","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":44246,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in L* (A), a* (B), b* (C), and hue (D) in cantaloupe flesh color during the storage period. Data are means of three replicates. Different letters in the same day indicate significant difference by the Duncan multiple range test (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/b31c0a15d128bc425be4708d.jpg"},{"id":85862843,"identity":"269ffcea-f475-4a20-a451-c1e919833ecc","added_by":"auto","created_at":"2025-07-02 12:37:40","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":50082,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in TSS (A), sucrose (B), fructose (C), and glucose (D) in cantaloupe during the storage period. Data are means of three replicates. Different letters in the same day indicate significant difference by the Duncan multiple range test (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/75145316b08e8143c2380ef7.jpg"},{"id":85862276,"identity":"978037d7-9069-4acd-bea2-a88b6e01d784","added_by":"auto","created_at":"2025-07-02 12:29:40","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":37757,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in TA (A) and vitamin C (B) in cantaloupe during the storage period. Data are means of three replicates. Different letters in the same day indicate significant difference by the Duncan multiple range test (\u003cem\u003eP \u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/dbf440ab8a3a99c563e480b1.jpg"},{"id":87315253,"identity":"2d646bdd-4f4d-4a1f-abda-e8dd05c16453","added_by":"auto","created_at":"2025-07-22 15:38:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":864204,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6967879/v1/3ed6f918-e55a-4dbc-9792-4efb096f3fea.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons","fulltext":[{"header":"Introduction","content":"\u003cp\u003eMelon (\u003cem\u003eCucumis melo\u003c/em\u003e L.) is an agricultural commodity of high economic value and ranks fifth among the most important fruits worldwide [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Among the different types of melon, cantaloupe is the most popular among consumers [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Andrade et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] describe cantaloupe melon as having a netted skin with generally orange and thick flesh characterized by a fragrant aroma. Cantaloupe is classified as a climacteric fruit, making it susceptible to postharvest damage [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. This damage can arise from various factors, including physiological, microbiological, chemical, and physical activities [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Common issues include bruising, rot, chilling injury, freezing injury, and surface shrinkage. These problems can occur both in the field and during distribution and storage, significantly reducing the fruit's commercial value. Without appropriate treatment, melons can deteriorate and rot approximately ten days after being stored in an ambient room [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEffective postharvest handling strategies for melon fruit are essential for superior quality and extended shelf life. Research by Wardani et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] indicates that cantaloupe melons harvested early, specifically at 32 days after anthesis (DAA), 10 days earlier than the recommended harvest time, demonstrate a longer shelf life than fully ripe fruit. However, early-harvested melons often have lower quality, particularly regarding sugar content, as their carbohydrates are primarily starch (polysaccharides) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Additionally, the flesh color of cantaloupe melons harvested early is paler than those harvested at full ripeness, making them less appealing to consumers [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Consumers prefer cantaloupe melons with attractive flesh color, appropriate moisture levels, sweetness, a crunchy texture, and pleasing aroma [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The primary sugars found in cantaloupe melons are sucrose (58.1%), fructose (25.6%), and glucose (17.5%), with total soluble solid (TSS) content ranging from 11 to 12 \u0026deg;Brix [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Therefore, it is necessary to implement strategies to enhance the postharvest quality of early-harvested cantaloupe melons.\u003c/p\u003e \u003cp\u003eOne effective technology for improving the postharvest quality of melon fruit is the application of ethylene. Ethylene is a plant hormone that accelerates fruit ripening. In climacteric fruits, ethylene ensures uniform ripeness and enhances fruit quality. Controlling ethylene production and exposure can significantly impact the ripening process. The application of ethylene in postharvest management can effectively regulate this process. Furthermore, the concentration of ethylene used is vital for achieving optimal fruit quality. Gao et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] reported that the optimum ethylene concentration for postharvest treatment of melon fruit is 100 ppm. However, previous studies have not sufficiently considered the timing of ethylene application. Therefore, further research is necessary to explore how the timing of ethylene application affects the postharvest quality of early-harvest melons. The timing should be primarily evaluated based on the climacteric peak period of cantaloupe melons. Consequently, the main objective of this study is to identify the optimal timing for ethylene application to improve the postharvest quality of early-harvest cantaloupe melon.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePlant Material\u003c/h2\u003e \u003cp\u003eMelon (\u003cem\u003eCucumis melo\u003c/em\u003e L. var. Cantaloupe) was cultivated in a greenhouse in Jasinga, Bogor, Indonesia. The melons were harvested 32 days after anthesis, which is 10 days earlier than reported in previous studies. After harvesting, the fruits were taken to the laboratory at the Department of Agronomy and Horticulture, IPB University. Only undamaged melons of uniform size were selected for the study. The fruits were then rinsed with a sodium hypochlorite solution at 100 ml per liter. Subsequently, the melons were exposed to ethylene based on the assigned treatments and stored at room temperature (25\u0026ndash;28\u0026deg;C). Each treatment group contained approximately 30 fruits, divided into three replications of 10 fruits each.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEthylene Treatments\u003c/h3\u003e\n\u003cp\u003eThe type of ethylene used in this study was Ethrel 480 SL (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e6\u003c/sub\u003eClO\u003csub\u003e3\u003c/sub\u003eP). The concentration of Ethrel used was 100 ppm [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Melon fruit was treated without exogenous ethylene application (control) and exogenous ethylene application (Ethrel) at a concentration of 100 ppm with application times of 0, 3, 6, and 9 (d0, d3, d6, and d9) days after harvesting (DAH), so there were five treatments. In the application of exogenous ethylene, melon fruit was soaked in exogenous ethylene solution for 1 minute and air-dried, then stored in a room at room temperature (25\u0026ndash;28 \u003csup\u003eo\u003c/sup\u003eC). The treated fruit was then observed for 21 days after treatment.\u003c/p\u003e\n\u003ch3\u003eMeasurements of Respiration Rate and Ethylene Productions\u003c/h3\u003e\n\u003cp\u003eRespiration rate and ethylene production were measured following the method suggested by Arif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The respiration rate and ethylene production in cantaloupe melons were measured using a Gas Analyzer (Merck Felix, type F-950) by flowing air in a sealed glass bottle into the Gas Analyzer with an airflow rate of 70 ml min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (Felix's instrument). Measurements were performed by placing two whole melons in a closed 6 L jar for 60 minutes. The respiration rate was expressed as ml kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and ethylene production was expressed as ppm kg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eMeasurements of Weight Loss and Softness\u003c/h3\u003e\n\u003cp\u003eThe weight loss of the fruit was calculated using the method proposed by Arif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The percentage of weight loss was determined using the following formula: Weight loss (%) = ((Weight before storage - Weight after storage) / Weight before storage) x 100%. The results were expressed as a percentage (%).\u003c/p\u003e \u003cp\u003eFruit softness testing was conducted using the method described by Sun et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. A Stanhope-SETA penetrometer was employed with a total load of 152.5 g, which included a 102.5 g cone and a 50 g weight. The needle puncture, with a probe size of 2 mm, was applied for 10 seconds. Measurements were taken by inserting the penetrometer needle into the fruits base, middle, and tip. To calculate the softness, the penetration depth of the penetrometer needle was recorded, and the following formula was applied: r x 0.1 M x T, where r\u0026thinsp;=\u0026thinsp;average penetration depth value of the penetrometer needle; M\u0026thinsp;=\u0026thinsp;weight of the weight load; T\u0026thinsp;=\u0026thinsp;penetration time of the penetrometer needle (10 seconds). The softness was represented in mm g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eMeasurements of Flesh Color\u003c/h3\u003e\n\u003cp\u003eThe color were measured according to the method described by Arif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], with slight modifications. The color measurement was carried out in three different parts of the cantaloupe fruit (i.e., base, equatorial, and tip section) using the CR-400 Chroma Meter (Minolta Japan). The chromameter is calibrated with a white field. The color of cantaloupe rind and flesh were expressed L*, a*, b* and hue values. Then, the average was determined.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eMeasurements of Total Soluble Solids (TSS) and Sugar Content\u003c/h2\u003e \u003cp\u003eThe total soluble solids (TSS) were measured from triplicate extracts of melon cantaloupe juice using an Atago DR-A1 digital refractometer (Atago Co. Ltd., Tokyo, Japan) at a temperature of 28\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u0026deg;C, following the method suggested by Arif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The TSS results were expressed in degrees Brix (\u0026deg;Brix).\u003c/p\u003e \u003cp\u003eTo measure sugar contents (glucose, fructose, and sucrose), we followed the method described by Arif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. A 5 g sample of melon was taken, and 20 ml of distilled water was added. The mixture was stirred with ultrasonics for 30 minutes and then filtered using a microfilter. The resulting supernatant was analyzed using a Dionex Ultimate 3000 high-performance liquid chromatograph (HPLC). The contents of glucose, fructose, and sucrose are expressed as percentages.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMeasurements of Titratable Acidity (TA) and Vitamin C\u003c/h3\u003e\n\u003cp\u003eArif et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] described the NaOH titration method for determining total acidity (TA) content. To measure TA, the extract is titrated with 0.1 N NaOH and expressed as a percentage of malic acid equivalents. The equivalent weight (EW) of the acid used in the TA calculation for melon fruit is based on malic acid, which has a value of 67. The formula for calculating the TA content of cantaloupe is as follows:\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAfcAAAArCAYAAABl/sHHAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAA9USURBVHhe7Z1Jqx5FG4Y73w/QOKxCCOJxp6ALBwgqGNCIgrhQ4rARhEjchcQpmpUJJiZbRxTcGBWzECHiAApGBCWLCC5jEAlZxeEf5OurTt8nT+pUD++Qc3I69wVFd1V3DV39dt1VT1X3u+58TWWMMcaY0fC/ZmuMMcaYkWBxN8YYY0aGxd0YY4wZGRZ3Y4wxZmRY3I0xxpiRYXE3xhhjRsYVLe6ffvppddNNNzW+leH555+v1q1bl9ybb77ZhC7y4IMPLh3jvD6Ir/PzOPkxrhVi/riffvophZeYpm6IQ164/PqGEuuhq3x9UIah6ai+RCyD6k5wjTrWd43x3NyRbrwf5Hn69Oll5wDlV9i09WqMuYLgPfcrkePHj/N+//mFhYUmZGXZunVryp9yRD755JNlYSWIn5c9D/vjjz9SHmwj5NF13Yo3Kbom0ocdO3YkNwkHDx5MDqaJL/JrKNWDIA+Ol66ZeirFpYxt6eVwLnUT4R7H6yzdNx0XMY4xxnRxxY7c77777qoWoca38tx4441V3ahX99xzTxMyHEZz33zzTXXq1KkmZJGvv/66qoVh0Ki/iwceeCClMynkX4tU46uqt99+O23jyJeRZ0SjV/H99983e4vxlUaJrrQOHz5c1UKY9oG6Pnr0aOO7GPKohbPxXQx1UQtz2rZBnvEaIS9bDr+/F198Me0/9dRTF9U3vw3y/PPPP5uQRX7++efqsccea3zGGNPOmhf3aMbErAkyscp8GU2fbSZNHSc9mUBllpY/5kUYDbr8EYXhiNMGooIYqtw50RSLww+vvfZaavxLIGLvvPNO45scrgkhQ2CE8paJmTrM66KN3bt3p/KKukOZ4gDxPvrooyUBJ5xOy0svvZT2yUNmfuUdOwJdaX377bfV5s2b0z7ce++9F3UcJqGv00SeP/7445LAU9auzhFljZ0BhB5i2DPPPLPsPiL28b4YY0wba17caezUkNIIAyMiRm1s1SAjBJyHcJQEPjbGcVSPwGh0jeiRDgJK40uDjh+BVpoINWkRThnaBEEgQghaqUz79u1L5VCe+IH02xr5G264IW1jp4LyIYJyTz75ZHNkOQgkQijUwaEOKCvlef/99y+qC5WrhMoZOwDEoxzE0z0Dwum0UG/sU3dcK+Ulb/YRvCiCbWnF+ylyS8ckMLLP845I4CkLZc3vD/dY9V+y1lCPxBfaV71xP+N9McaYLkZhlqchRRRiQ7hp06a0T4OM2RM4D+FAnIZCHJlsJQ4IKKKnUaIEkHxpxCWmdCTwd0H6CCbnRgEExOqJJ55I+xLtaVBnQ65rOoJr3LhxY+O7cM3UAWXlGOnFuuiD+sGkLNTx6BNbrp+6pLzkjctFcGhas0KHj98OHQ3lmaPws2fPpm2E36fqvzQFgHDnI3XiHDlyJO0zpXDnnXemfWOM6WM0c+6MpGNDiCiqsd2wYUPagkT/UqBGPQoprg/KSkPeNv+OOCL+AsFrExhMtxxHCKehNOKdJ5Rbo36sBG1TEm3EzkRXWtRBjjph04IliHTJM4e8mX6gLPwW2+4P0FFQp03IL5M9HdItW7YkK4CY9p4aY648RiPuNI75yEeN4a+//pq2YtZGvg11Iroa9jZkUo4mc8zSMvMyahTbt29PFoFSPpzL8WkpieI8IX2NshE5BLFv6iJC50UC35UWAhytBYz2EctZ0fRA7GyRJ4JOGYAylToAfWikTllJi8Vz5NU2FWCMMW2MRtwBky1z13F0TlgUTEZ4NMQ56gho9M15NKyTjCxJA8GJYjWJcOXmWjorModHGEEiBLmAqKxahT0NpHnmzJnGNx8QOy1uyy0ZiJimN9qIZnjqRCvGu9Ji5KvpFzpBMd4scC/yaQ3yzEfiQ6YJuF+xg8bvMnZQ9Xvi9+tV8saMC55/rcPBldZdtcG5vXHrBnIZBA9xtfA0MZZTi+qg97XnSd3opnLl1EK4VOZ6BJzCdC6O40CZFcZ+3bAuvXMsl8eLcZS2/DFM5OnldcT5CotpUxa2Kitwro7jOF/kxyg3xDRxef6cF/NQvkojxs3rIp6rdLlewoeguDjFYUvaCtd1DCGWL14n/q56pMycn4dFqMc8rESsk9zF+wX6bcSyUrah9TcJ5EH+pN/GyZMnz99+++2pTJQhliuyZ8+e89dcc006j/1z5841RxbhPqgeON4Gx44dO9b4jBk3tEGxHcqhPeCZ2LZtWxNShjRKz3FR3HmgY8OlxlXw8NIwtD3saqTyxsusDboa8knhNzCJIOdQllnit9ElamuRXFBFKZx7i4jyjLbVA8LO8XfffTf51VHKfxc0PGovyIv92GCpLSA/pVn6bXF8bPfEmC66xJ3nhmeC9q/tHMHxQeLOg5c/fETmoYzwILf1smnQ1ZOPnQSzNlCDPOu94wfX98Ps41KIO9c2NiGhnhHPCM8o4W33saseqHeEOoKQEy4k+LEdkIDrnpE+fkF58pEI5esbnRgzNngW+trHoeeUnuNlc+7MW2phUBfXXXdd9dBDDzW+C/z9999p0dGXX36Z/HwpzKwtmOutfxtTLQoTLAJj8Vt893xSmJOqG/405zzPRWVc2yzrEi5HPv7447TI77fffkt+nsOnn346LcTM12z0QRrU++OPP96ELHLfffelcL2y+cUXX6RtbAduvfXWqu7YpzUrbfz333/N3iKsS3nrrbcanzFmHsx9Qd2HH36YPihCB6HuUaQFQkNWj9NgxAUCbW6SBW5mNoYsCmuDBWZ9C+X6oGOAEOPyBWvmYuhsS+B5liTsiO2k6NsMt9xyS9qKm2++OW31FsJnn31W1aP7tB/hffyu7zusX7++2VsUdt5yoPzGmPkxV3FntPD5558vNcT67OiQ0TudATXkXW6WkaAxYwaBpEPF9xJYeT+NsEeuuuqqZq+dPlHWKn86HFgEEP1HH300hWGNoYw8+xzjFVU68K+++mo6boyZnrmKO6P2Xbt2Nb5FwdboHeG/VOSjezu7Mbs2eMYYCR8/fjyZxWWiX0306uAjjzxS3XbbbdWePXtS55+y8Yrjc889l8qNyf+FF16ozp07lywCk7wWZIxZztzEnQf0wIEDaX40NkQyzyH8Xcxili+N8O3sxupK8PzJFE+nOp+DX00Q83/++SeVff/+/amsb7zxRvX666+n47/88kv177//Vvfff3+yBLDWAwugMWZ65ibuiPfLL7+8rCGiJ84CG4Sfh7oNm+WNmZ58jj3OwU/6xUSsbRC/8Afy64NE27ZtK86tE6Y0Suzdu7d65ZVXlkz6v//+e9pq4R9fIDxx4kTaN8ZMx1zEHdHma2DPPvtsE3IBHmBEn5553+jdGDMdCHk+xy6Bn3S1POksLCws+4tc/ITTEQfNnWv1PGi/9BVIeO+999Kf5MSyauGeOiG8ZVFaqGeMGU6vuPPAqXdeMvEh7PTEGZ23oYeX0XtsCIwx80Gj4Jy2cAlp23/cM2fPc69XEBFl/PEVN8ztjNB37tyZ2gHSZJ+w0tsNtB+4/Nhdd92V2o/vvvsupUOe+Wt4OaTDNF1p8d0dd9yRXA7nEqfUjl177bWtcTiWWz+++uqrlBb1ksP1dcVhG+E8zi/V2TzToqxdcdrqkmM586z/K+Fe6nOxk+gfzwKO/0ZhOymd4k6B6KkLFsTkc96YA1kwhxnt+uuvb0IvQBoPP/xw2mf0zkpeL5YxZvWIzzWCXWp0GJ0fO3YsvfHC8Q8++CAt1NOoXWAZoCHl2We0zXw5YTk0TnGePUIH5IcffqgOHTqU0tmxY8eg7xDQIbj66qsbXz+c2zYIoUFu6wiV0JsEpfxJC4aWTecpXmSeaenYkLcgBHVSSgvmWf9jv5dd5S3B88izgK6im+xPqpvrzjORbVYcbpT+WYzVxH/99Vd6bWhSE+o08MoR3yIo9e4vFXQKt2zZ0ttoz1o2Rn3UZVs+fceNMWYl0EB51nVkbW3r3BbUmeHQK0PYtUiQV4Ik9Jcafgh8ZWyl4QfcJ6h9ZUOYu8xadJioy6586DQwpzvJv/UZY8xaw+K+CrDqOK4m5sMjrHReCRDZONVyOdFXNn0UqQSiz/zxkK/i6RzNJxtjzNiwuK8CvErEXGecQ2G0KZM84cxzyglGthxj1Em4zDr6spfSQ+jwa6v9NhS/dB4LRHQMMcRFP7BPGqCy4eL1cTyKacxTLsK1EaYRNvuM6lmzoeuOYMrPxT+WRU7Xt3v37s7OgjHGXGq05gUX28s+okaQRhHm3M3KU4/U079l4fJ/4SOsFrK0X49k07n8057O5x+3OM4+x9nXP3QpHLe1+Tch5SWIo3/tIl3lTxjHckgzhnN+9JM+EF/7KgdbysF+zBMHKrcgXfzkgYvHFJ6jvCLxWnQ8j8vxUnrGGLPW8ch9lWCkXtd/2mc0qpEvEK5RvMIxJWPKr8UzzRvrOK8msb9x48bkZ78WrLSvhRqagy6N3nnTgfzpAfJ1wVoIl732obwU/8yZM8XzKAtrB0irFs4UxmscubmdeHyoBLRwLqZVC3Nalb1hw4bkz/PJOXv27DJzPovmVHeUn7qj3BGO5x9qMcaYMWBxX2UQcoQSF80yCFqnyWVCcvEDiSZ5Uw45iXlk+/btS0KIcPK60tGjR1MamzZtSuH8ixzCHNMqrXrnAyd6v1plKOU5lFy0gTcPYt1RNnWAjDFm7FjcVwHmnuMoGmFDLFnFDYwoeV8YcYwL72YBAddIWEhQGfn2wToBBFlizlfG8DMy5y8+gXIj/H0g+IitRviyNExLSbRVp+SBo3OSv6NtjDFjxeK+SmAKj2AeRzARfYR4lv9SF+pA0Jmgk1AaHRMePxWK9UCj6QjCyEiYv+9FnHH4EXOly7uW8Vvm5B8X0QkWumHC1+h+qOiWrA9AfOosQr6Y/pVH6fU46ljfSTfGmFFRN3xmhWGxVy1GaZGXnBaiQS1iS+FxX45zY7gWpcmxSIxtLdxLYSLG02KyGKaFbiVILx7P/YBfaZEu5HlSfvnliBfLm18T9aW0lW6EuMQRqoPoYjzSK6VjjDFjwF+oGyGMmLEMXK63llF1PhePxaDr4zN9cM1YIGTxwM80RLRWyJLBSB/rAZaS0poAY4xZ69gsb1YUBLb0frnWG0wLgs28ut6Bz6c94MiRI+k8TT1Y2I0xY8Uj95GBaC2EuenL8fYyamaNQWRe5cQqwDoAFv3xal+EhXusrOcTtUO+ZGeMMWsVi7sxxhgzMmyWN8YYY0ZFVf0f03ghDspubVgAAAAASUVORK5CYII=\" width=\"503\" height=\"43\"\u003e\u003c/p\u003e\u003cp\u003eRemarks:\u003c/p\u003e \u003cp\u003efp\u0026thinsp;=\u0026thinsp;Dilution factor\u003c/p\u003e \u003cp\u003eEW\u0026thinsp;=\u0026thinsp;Equivalent weight (malic acid).\u003c/p\u003e \u003cp\u003eThe vitamin C content was evaluated using the method described by Ismillayli et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. First, the flesh of the cantaloupe melon was mashed to release the juice, which was then filtered through a cloth. A 10 g sample of the juice was measured and transferred into a 100 ml volumetric flask, where it was diluted with distilled water. From this solution, 10 ml was taken and placed in an Erlenmeyer flask. Three drops of starch solution were added as an indicator, and the mixture was titrated with iodine until a stable dark blue color was obtained. The iodine used as a titrant had a normality of 0.01 N. In the formula for calculating vitamin C, the equivalent weight (EW) refers to the predominant acid in vitamin C, which is ascorbic acid (Ismillayli et al. 2020). The equivalent weight of ascorbic acid is 0.88.\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eData Analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using a one-way analysis of variance (ANOVA) for each storage day. Significant differences among the treatment means were determined using the Duncan Multiple Range Test (DMRT) at a probability level of 5%. Statistical analyses were performed using SAS Portable Version 9.1.3, and the results are presented as the mean of three replications.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003eRespiration Rate and Ethylene Productions\u003c/h2\u003e\n \u003cp\u003eOne of the key factors in determining the shelf life of fruit is its respiration rate and ethylene production. Ethylene is the primary hormonal trigger for the ripening of climacteric fruits, such as melons. In this process, there are both ethylene-dependent and ethylene-independent regulatory pathways that work together to manage ripening. Specific physiological processes during ripening are established as ethylene-dependent, while others function independently or are very sensitive to low levels of ethylene. For instance, in many fruits, including melons, ripening is marked by a temporary increase in respiration rates and an autocatalytic rise in ethylene production. Specific processes, such as climacteric respiration, stalk abscission zone formation, skin yellowing, and carotenoid content in Charentais-type Cantaloupe melon (cv. V\u0026eacute;drantais) are dependent on ethylene [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. Additionally, membrane damage and volatile compound synthesis are also partially influenced by ethylene [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eIn this study, the application of exogenous ethylene affected both the melons\u0026apos; respiration rate and ethylene production (Fig.\u0026nbsp;1). Cantaloupe melons treated with ethylene on days 0 and 3 of storage (d0 and d3) experienced a faster climacteric peak, occurring between days 3 and 6 of the storage period (Fig.\u0026nbsp;1A). They began to show signs of senescence from days 9 to 15. In contrast, those treated with ethylene on days 6 and 9 (d6 and d9) displayed a longer climacteric peak, lasting from days 6 to 12, with senescence starting on day 15 (Fig.\u0026nbsp;1A). Additionally, the rate of ethylene production followed a pattern similar to that of the respiration rate in melons during storage (Fig.\u0026nbsp;1B). Melon fruits treated with 100 ppm of exogenous ethylene tended to reach the climacteric peak earlier than the control. Furthermore, the ethylene production in melon fruit exposed to exogenous ethylene at the beginning of storage (from day 0 to day 6) was significantly higher. The d6 treatment maintained a low respiration rate and low ethylene production during the first six days of storage. This was because ethylene had not been applied to the melon fruit. However, after six days, both the respiration rate and ethylene production increased, which was expected to enhance the quality of the cantaloupe melons during storage. The rise in ethylene levels can stimulate positive physiological changes that improve the quality of the fruit without reducing its shelf life. By controlling ethylene levels, respiration can be reduced, starch degradation can be delayed, and the melons can develop more complex flavors while being less sweet, ultimately extending their shelf life [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. Therefore, applying exogenous ethylene at 100 ppm on day six was deemed appropriate to slightly elevate ethylene production and respiration rates in postharvest cantaloupe melons during storage.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003eWeight Loss and Softness\u003c/h2\u003e\n \u003cp\u003eWeight loss is one of the crucial factors related to fruit storage life because it can interfere with the visual appearance of the fruit [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e]. Due to respiration and evaporation, melon fruit loses water. In addition, melon fruit undergoes a respiration process during storage, requiring energy obtained from the breakdown of starch, amino acids, pectin, and other compounds. Higher respiration rates and ethylene production increase weight loss [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e]. In this study, weight loss in melon fruit increased with extended storage periods (Fig.\u0026nbsp;2A). Additionally, the weight loss observed in melons treated with d6 was lower than in the other treatments, with a reduction of 2\u0026ndash;6% (Fig.\u0026nbsp;2A). The weight loss in cantaloupe melon was \u0026lt;\u0026thinsp;20%, which is relatively low. The weight loss observed in melons in the d6 treatment was lower than in other treatments, with a reduction of 2\u0026ndash;6% (Fig.\u0026nbsp;2A). The addition of exogenous ethylene can accelerate the decomposition of cell wall membranes. Covalently bound pectin encourages an increase in water-soluble pectin, accelerates the degradation of hemicellulose and cellulose, and accelerates the decomposition of pectin bond ions so that the fruit becomes softer and higher weight loss [\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n \u003cp\u003eAs one of the basic parameters of postharvest quality, fruit softness affects shelf life and consumer acceptance. Ethylene plays an important role in fruit softening and firmness by activating cell wall-degrading enzymes, such as polygalacturonase, which hydrolyzes pectin in the cell wall, producing fruit softening. The higher in fruit softening during storage occurs because melon fruit is stimulated by ethylene during storage, so softening can increase with increasing ethylene concentration [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]. In this study, cantaloupe melon fruit softness increased during storage for all treatments (Fig.\u0026nbsp;2B).The softness of cantaloupe melon increased during storage for all treatments (Fig.\u0026nbsp;2B). The fruit treated with exogenous ethylene of 100 ppm at day 0 (d0) showed a faster softness increase than the other treatment (Fig.\u0026nbsp;2B). Conversely, the slowest increase in softness occurred for fruit treated with exogenous ethylene at 6 and 9 days into the storage period (treatments d6 and d9) (Fig.\u0026nbsp;2B). In the treatment of exogenous ethylene application of 100 ppm, the slowest increase in softness occurred in the fruit applied with exogenous ethylene on the sixth and ninth days of the storage period (treatments d6 and d9) (Fig.\u0026nbsp;2B). Therefore, exogenous ethylene treatment on day 6 can be considered to smaller weight loss and maintain the firmness of melon flesh with better quality.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003eFlesh Color\u003c/h2\u003e\n \u003cp\u003eThe lightness of melon flesh decreased over the storage period (Fig.\u0026nbsp;3A). Additionally, applying 100 ppm ethylene resulted in a faster decrease in lightness compared to the control. The treatment applied on day 6 (d6) exhibited a slower decrease in lightness than the 100 ppm ethylene application at other application times during storage (Fig.\u0026nbsp;3A). In contrast, the melon flesh\u0026apos;s redness (a*) value increased during storage (Fig.\u0026nbsp;3B). Specifically, the redness (a*) values for treatments d0, d3, and d6 showed significant increases at 7 days of storage compared to the control and d9 (Fig.\u0026nbsp;3B). Therefore, the 100 ppm ethylene treatment influenced the color of the melon flesh, making it appear more orange or red. At 7 days of storage, the b* value was most pronounced in the 100 ppm ethylene treatment across all application times, with increases ranging from 12.97 to 20.78 (Fig.\u0026nbsp;3C). Moreover, the hue value of the melon flesh exhibited a consistent downward trend throughout the storage period (Fig.\u0026nbsp;3D). The control treatment maintained a higher hue value than those subjected to exogenous ethylene application. Notably, the reduction in hue value for the d6 treatment was substantial, with a decrease of up to 8.89 (Fig.\u0026nbsp;3D).\u003c/p\u003e\n \u003cp\u003eFruit color is a key factor that influences consumer choice. During the ripening process, the pigmentation of the fruit\u0026apos;s flesh and rind determines its color [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e]. As fruit is stored for longer periods, its hue value decreases. In this study, the d6 treatment demonstrated the smallest decrease in hue value in melon flesh compared to other treatments. The addition of exogenous ethylene affected the hue of cantaloupe melon flesh. This study\u0026apos;s most effective concentration for reducing hue was 100 ppm, applied on the sixth day of the storage period. This treatment resulted in a color change of the fruit flesh from yellow to orange. It is hypothesized that applying exogenous ethylene on the sixth day is optimal because the melon fruit is expected to reach its climacteric peak by that time. According to Wardani et al. [\u003cspan class=\"CitationRef\"\u003e7\u003c/span\u003e], early-harvested cantaloupe melons typically reach their climacteric peak on the eighth day after harvest. The yellowish color change in the flesh of climacteric fruits during storage is significantly influenced by both the ethylene produced by the fruit itself and the additional exogenous ethylene. Paul et al. [\u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e] noted that adding exogenous ethylene to cantaloupe melons can accelerate the degradation of the fruit flesh, increase internal ethylene production, and hasten ripening.\u003c/p\u003e\n \u003cp\u003eIn this study, we observed that the lightness value of melon flesh (L*) decreased during storage. This decrease in L* indicates that the fruit is ripening, as the color of ripe flesh generally becomes deeper. This finding aligns with the research by Vanoli et al. [\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e], which demonstrated a decrease in the L* value as fruit ripeness increased. Additionally, Kasim and Kasim [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e] noted that the decline in the L* value after several days of storage is attributed to changes in the color of the melon flesh, which transitions from bright green to yellow-orange. Therefore, treating cantaloupe melon fruit with 100 ppm of ethylene on day 6 (the d6 treatment) is recommended to enhance color characteristics during storage.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\n \u003ch2\u003eTotal Soluble Solids (TSS) and Sugar Content\u003c/h2\u003e\n \u003cp\u003eThe total soluble solids (TSS) of cantaloupe melon fruit increased during storage, as shown in Fig. 4A. The most significant increase in TSS levels occurred in the d6 treatment after 14 days of storage, where the TSS value was 2.34 \u0026deg;Brix higher than the control. Additionally, on the seventh day of storage, there was no significant difference in TSS content between the d9 treatment and the control (Fig. 4A). The sucrose content of cantaloupe melon fruit also increased following ethylene application during storage (Fig. 4B). In the d6 treatment, the sucrose content was higher than in the other treatments. Furthermore, on the seventh day, the cantaloupe melon fruit treated with d6 rapidly increased sucrose content, 12-fold higher than the control. The melon fruit\u0026apos;s fructose and sucrose content increased during storage (Figs. 4C and 4D). Finally, in the d6 treatment, the levels of fructose and glucose in the melon fruit were higher compared to the other treatments.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\n \u003cp\u003eClimacteric melons are classified as fruits that can continue their ripening process even after being harvested but cannot increase their TSS content if not treated to induce it [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Climacteric melons, including cantaloupe melons, can higher their TSS content due to exogenous ethylene. TSS is an important indicator of fruit quality and consumer acceptance [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. In this study, TSS and total sugar in cantaloupe melons increased during storage (Fig.\u0026nbsp;5). In addition, the TSS, sucrose, fructose, and glucose content of melons in the d6 treatment showed higher values than the other treatments. This increase can presumably occur because exogenous ethylene applied at the beginning of storage can process starch into sugar earlier, so the accumulation of soluble solids occurs faster. After reaching the highest TSS peak, cantaloupe melons experienced a decrease in TSS. Based on research by Lucchetta et al. [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e], the reduction in TSS in cantaloupe melon fruit at the end of storage occurred because the fruit used sugar to help aerobic respiration and senescence process activity.\u003c/p\u003e\n \u003cp\u003eThe primary components of the soluble sugar fraction in ripe melon fruit are sucrose, glucose, and fructose. At harvest time, cantaloupe melons have a sugar content ranging from 23.23 to 61.40 mg/g [\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e]. Other climacteric fruits, such as tomatoes, show an increase in total sugar content of 1.5% when transitioning from the green to red ripeness phase [\u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. During storage, mango fruit can experience an increase in total sugar of up to 28.55% [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e]. This increase in total sugars is influenced by ethylene, which plays a significant role in ripening. According to Gao et al. [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e], exogenous ethylene can enhance the sucrose content in fruit. In this study, the sucrose content of melon fruit in the d6 treatment reached 2.17%, which is 12 times higher than the sucrose content in the control group. Introducing ethylene and applying it to the fruit approaching the climacteric peak (after 6 days of storage) can boost the production of both endogenous sucrose and ethylene. Gao et al. [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e] noted that the increase in sucrose content is associated with the expression of the CmSPS1, CmACO1, and CmMYB44 genes, which are activated by the regulatory activities of the sucrose synthase (SS) and sucrose phosphate synthase (SPS) enzymes. Moreover, Braun et al. [\u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e] stated that sucrose serves as a source of metabolism for constructing carbon and energy frameworks that support plant growth and development, and plays a crucial role in enhancing the taste quality of melon fruit. Daryono and Genesiska [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e] emphasized that sucrose accumulation contributes to taste quality by increasing the total sugar content in the fruit.\u003c/p\u003e\n \u003cp\u003eIn this study, melon fruit\u0026apos;s fructose and sucrose content increased during storage. Generally, fructose accumulation was less than that of sucrose during the growth process and either decreased or remained unchanged during ripening. The average sucrose content in the mesocarp tissue was 58.1%, which was consistently higher than the glucose content at 17.5% and the fructose content at 25.6% [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e]. This trend occurs because fructose accumulation happens at the beginning of fruit development, when the fruit is still unripe, and is subsequently converted into sucrose. As a result, sucrose becomes the dominant sugar in ripe fruit [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. The increase in glucose content during the storage of cantaloupe melon was not as pronounced as the increase in sucrose content. The increase in glucose in cantaloupe melon is dependent on its sucrose content. Furthermore, exogenous ethylene application can enhance sucrose content and boost glucose and fructose levels. According to Yu et al. [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e], in strawberries, the enzyme \u0026beta;-fructofuranosidase catalyzes the breakdown of sucrose into fructose and glucose within fruit cells. The availability of glucose in the metabolic process activates the enzyme phosphoglucomutase, which can be stimulated by ethylene treatment. Phosphoglucomutase is responsible for converting UDP-glucose into glucose-6-phosphate via \u0026alpha;-D-glucose-1-phosphate, resulting in the production of glucose.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\n \u003ch2\u003eTitratable Acidity (TA) and Vitamin C\u003c/h2\u003e\n \u003cp\u003eTitratable acidity (TA) and vitamin C are essential indicators of fruit quality. As illustrated in Fig. 5, both TA and vitamin C contents in melon fruits generally decreased during storage for all treatments. Specifically, the melon fruits in treatment d6 exhibited the lowest TA content compared to the other treatments throughout the storage period (Fig. 5A). Conversely, the melon fruits in the d6 treatment demonstrated higher vitamin C content than the other treatments during storages (Fig. 5B).\u003c/p\u003e\n \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\n \u003cp\u003eTitratable acidity (TA) and vitamin C are important indicators of fruit quality. In this study, we observed that the TA and vitamin C content in melon fruits decreased during storage. Specifically, melon fruits in the treatment labeled d6 exhibited the lowest TA content compared to the other treatments throughout the storage period (Fig.\u0026nbsp;5A). This suggests that, during storage, melon fruits are still undergoing respiration, where the TA content is inversely related to sugar content. The increased ethylene production in the cantaloupe melon fruits from treatment d6 is expected to enhance sugar content while slightly lowering TA during ripening. During respiration, organic acids are converted into sugars, and their derivatives or utilization during storage can cause a reduction in TA [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. TA tends to increase during the early stages of ripening and decrease towards the end [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e]. Moreover, Cocco et al. [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e] reported that applying exogenous ethylene can lower TA in climacteric fruits, speeding up the ripening process and promoting the accumulation of moisture and sugars. In addition to TA, vitamin C is a vital nutrient prone to oxidation during storage [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. In this study, the melon fruits subjected to treatment d6 showed higher vitamin C content, which was maintained during storage (Fig.\u0026nbsp;5B). Therefore, the d6 treatment effectively preserved vitamin C content in postharvest cantaloupe melons.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eExogenous ethylene treatment at a concentration of 100 ppm applied 6 days after harvesting (d6) significantly enhances the quality and shelf life of early-harvested cantaloupe melons. This study demonstrates that the 100 ppm ethylene treatment at d6 accelerated the increase in sugar content (sucrose, fructose, and glucose) and resulted in color degradation in the melon flesh. Additionally, by the seventh day of storage, the sucrose content in the d6 treatment group was 1-1.8% higher compared to the other treatment. The d6 treatment also increased the edible portion of the melons while maintaining titratable acidity (TA) and vitamin C content. Furthermore, the shelf life of melons treated at d6 extended to 12 days of storage. Thus, applying exogenous ethylene at a concentration of 100 ppm at d6 is an effective method to improve the sugar content and overall quality of early-harvested melons.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflict of Interest\u003c/h2\u003e \u003cp\u003eThe Authors declare that there are no conflicts of interest.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization: KS, ABA, SS. Methodology: KS, ABA, NPZKW, SS, DPH, data curation: ABA, NPZKW, DPH, SMW, SP, W. Investigation: KS, ABA, NPZKW, SP. Visualization: KS, ABA, NPZKW, SMW, SP, W. Writing \u0026ndash; original draft: KS, ABA, NPZKW, SS, DPH, S. Writing \u0026ndash; review \u0026amp; editing: KS, ANA, NPZKW, SS, S.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThank you to the Ministry of Education, Culture, Research and Technology Republic of Indonesia for funding this research through the 2024 Masters Research Scheme with contract number 22262/IT3.D10/PT.01.03/P/B/2024.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eOrtiz-Duarte G, P\u0026eacute;rez-Cabrera LE, Art\u0026eacute;s-Hern\u0026aacute;ndez F, et al (2019) Ag-chitosan nanocomposites in edible coatings affect the quality of fresh-cut melon. Postharvest Biol Technol 147:174\u0026ndash;184. https://doi.org/10.1016/j.postharvbio.2018.09.021\u003c/li\u003e\n\u003cli\u003eAyres EM, Lee SM, Boyden L, et al (2019). Sensory properties and consumer acceptance of cantaloupe melon cultivars. 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Postharvest Biol Technol 159:1-11.\u003cem\u003e \u003c/em\u003ehttps://doi.org/10.1016/j.postharvbio.2019.111000\u003c/li\u003e\n\u003cli\u003ePaul V, Pandey R, Srivastava GC (2012) The fading distinctions between classical patterns of ripening in climacteric and non-climacteric fruit and the ubiquity of ethylene-An overview. J Food Sci Technol 49(1): 1\u0026ndash;21. https://doi.org/10.1007/s13197-011-0293-4\u003c/li\u003e\n\u003cli\u003eVanoli M, Cortellino G, Picchi V, et al (2023) Non\u0026shy;destructive determination of ripening in melon fruit using time\u0026shy;resolved spectroscopy. Adv Hortic Sci 37(1):75\u0026ndash;82. https://doi.org/10.36253/ahsc-13943\u003c/li\u003e\n\u003cli\u003eKasim R, Kasim MU (2014). Biochemical and color changes of fresh-cut melon \u003cem\u003e(Cucumis melo\u003c/em\u003e L. cv. Galia) treated with UV-C. 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J Pharmac Phytochem 10(2):883\u0026ndash;886.\u003c/li\u003e\n\u003cli\u003eBraun DM, Wang L, Ruan YL (2014) Understanding and manipulating sucrose phloem loading, unloading, metabolism, and signalling to enhance crop yield and food security. J Exp Bot, 65(7):1713\u0026ndash;1735. https://doi.org/10.1093/jxb/ert416\u003c/li\u003e\n\u003cli\u003eDaryono BS, Genesiska (2012) Pewarisan karakter fenotipik buah melon \u003cem\u003e(Cucumis melo\u003c/em\u003e L.) kultivar gama melon basket hasil teknik seleksi buah. J Ilmu Pengetahuan dan Teknol Tepat Guna 2:9\u0026ndash;18.\u003c/li\u003e\n\u003cli\u003eVillanueva MJ, Tenorio MD, Esteban MA, et al (2004) Compositional changes during ripening of two cultivars of muskmelon fruit. Food Chem 87(2):179\u0026ndash;185. https://doi.org/10.1016/j.foodchem.2003.11.009\u003c/li\u003e\n\u003cli\u003eYu JQ, Li ZT, Chen S, et al (2024) Analysis of ethylene signal regulating sucrose metabolism in strawberry fruits based on RNA-seq fruit kept at ambient conditions. Food Chem 405:134908\u003cem\u003e.\u003c/em\u003ehttps://doi.org/10.1016/j.foodchem .2022.134908.\u003c/li\u003e\n\u003cli\u003eGebregziabher AA, Supriyadi S, Indarti S, et al (2021). Texture profile and pectinase activity in tomato fruit (\u003cem\u003eSolanum lycopersicum\u003c/em\u003e, servo f1) at different maturity stages and storage temperatures\u003cem\u003e. \u003c/em\u003eJ Agro Sci\u003cem\u003e \u003c/em\u003e9(1):20-34. 10.18196/pt.v9i1.9139.\u003c/li\u003e\n\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":"Fructose, Glucose, Physiology, Storage, Sucrose","lastPublishedDoi":"10.21203/rs.3.rs-6967879/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6967879/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMelon (\u003cem\u003eCucumis melo\u003c/em\u003e L. var. Cantaloupe) is a climacteric fruit susceptible to postharvest damage. Early fruit harvesting can increase the shelf life of melon fruit, but early harvested fruit has low sugar content, and the color of the fruit flesh is less attractive. This study evaluated the effects of exogenous ethylene and its application time in increasing the sugar content and quality of early harvested melon during storage. Melon fruit was treated without exogenous ethylene application (control) and exogenous ethylene application (Ethrel) at a concentration of 100 ppm with application times of 0, 3, 6, and 9 (d0, d3, d6, and d9) days after harvesting (DAH). In the exogenous ethylene application, melon fruit was soaked in an exogenous ethylene solution for 1 minute and dried in air. Furthermore, melons were stored in an ambient room (28\u0026thinsp;\u0026plusmn;\u0026thinsp;1 ◦C and 80\u0026thinsp;\u0026plusmn;\u0026thinsp;5% RH) for 21 days. The results showed that 100 ppm ethylene treatment at 6 DAH (d6) accelerated the increase in sugar content (sucrose, fructose, and glucose) and color degradation in melon flesh. The d6 treatment also maintained the titratable acidity (TA) and vitamin C content. In addition, the shelf life of melons in the d6 treatment reached 12 days of storage. Therefore, exogenous ethylene treatment of 100 ppm at 6 DAH can be considered an appropriate treatment to improve the sugar content and quality of early harvested melons.\u003c/p\u003e","manuscriptTitle":"The Timing of Exogenous Ethylene Application Affects the Sugar Content and Quality of Early Harvested Melons","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-02 12:21:34","doi":"10.21203/rs.3.rs-6967879/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":"b990a1a5-1f1e-4325-b11d-e7ae3aae6241","owner":[],"postedDate":"July 2nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-22T15:38:25+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-02 12:21:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6967879","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6967879","identity":"rs-6967879","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}