Peel Color Change Research Articles

Development of Pericarp-Based Coatings from Corn Nixtamalization Residue for Stone Fruits: Applications for Peach and Tejocote

This study investigated corn pericarp, a by-product of the nixtamalization process, in developing sustainable films for fruit coatings. These films were evaluated for their optical, structural, barrier, and mechanical properties. The results showed that the pericarp films were transparent, had heterogeneous surfaces, and exhibited favorable mechanical and barrier properties, suggesting their potential as fruit coatings. The pericarp films significantly extended shelf life when applied to peaches and tejocotes postharvest. The films slowed the maturation process, as evidenced by minimal changes in peel and mesocarp color for up to five days for tejocotes and even longer for peaches. Additionally, coated fruits showed slower rates of weight loss, firmness reduction, and decreases in titratable acidity, total soluble solids, and total sugar content compared to control samples. These findings demonstrate the potential of corn pericarp films as effective coatings for extending the shelf life of stone fruits.

Changes in Nutrient Content and Physicochemical Properties of Cavendish Bananas var. Pei Chiao during Ripening

Banana is a typical tropical fruit that is widely cultivated in tropical and subtropical regions, and consumed daily because of its superior nutritional profile. This study aimed to investigate the changes in bananas’ physicochemical properties and nutritional composition from ripening stages 1 to 9. The analysis included color (peel and flesh), texture, total starch content, resistant starch content, free sugar content, minerals (calcium, magnesium, potassium, sodium, iron, phosphorus), and vitamin content. At the same time, the browning enzyme activities of polyphenol oxidase (PPO), peroxidase, oxalic acid, and tannin were also measured. In this study, the banana peel gradually changed from dark green to light green to yellow during the ripening process, eventually appearing with many black spots, while the pulp color changed from white to light yellow and decreased in brightness. The pulp became softer with a prolonged ripening period, which was inconsistent with the time point of peel color change (ripening period 4–5). However, total starch content decreased from 74% to 31%, resistant starch originally at 32% gradually decreased to 5%, and free sugar content gradually increased with increasing ripening period. Vitamin C content and PPO activity decreased significantly during the ripening period, while other vitamins and minerals did not change significantly. In contrast, oxalic acid, tannin content, and peroxidase activity were negatively correlated with the ripening period. Therefore, this study reveals the changes in the nutrient content of bananas at different ripening stages, which may provide helpful information for researchers and producers to identify suitable raw materials for producing stable and high-nutrition-value banana-related foods during the peak raw material abundance seasons while reducing business risk.

Evalution of co-culture system on Debaryomyces hansenii and Bacillus atrophaeus strains and its efficacy on disease control and quality maintenance of postharvest fruit

Microbial antagonists are used to manage both pre- and postharvest diseases of fruit crops. Mixing two types of antagonists has been reported to enhance the viability, stability, and biocontrol efficacy of each strain used individually. In the present study, a co-cultivation system for Debaryomyces hansenii (Y-1) and Bacillus atrophaeus (TE-7) strains was evaluated, and the regulatory mechanism associated with antagonistic activity and postharvest disease control in mango and litchi fruits was investigated. Results indicated that the optimized co-cultivation system for Y-1 and TE-7 (Y + T) significantly promoted the growth of both strains, compared to single cultures, and improved their ability to adapt to co-cultivation conditions. Non-targeted metabolomics revealed that characteristic metabolites, including N-Acetyl-L-glutamic acid, adenine, umbelliferone, and cucurbitacin B significantly accumulated in co-culture, which involved in citrate cycle (TCA cycle), amino acid biosynthesis, phenylpropanoid biosynthesis, and alkaloid biosynthesis. Subsequent in vivo and in vitro assays indicated that the Y + T system, relative to the use of the individual strains, significantly enhanced the inhibition of pathogen growth, increased disease control, and also decreased weight loss and changes in peel color. The co-culture also enhanced the content of total acids (TA) and total soluble solids (TSS) in mango and litchi fruits compared to the control group. These results suggest that the Y + T co-cultivation system is highly effective in antagonistic protection, disease control, and quality maintenance of postharvest fruit. Our study provides new insights into the interactions that occur between biocontrol microorganisms in a co-culture system, and information that can be used for the development of improved strategies for the postharvest preservation of fruit.

Enhancing postharvest quality and extending storage life of Booth 7 avocado (Persea americana Mill.) fruit through sodium nitroprusside (SNP) application during low-temperature storage

Postharvest quality plays a crucial role in marketability, consumer acceptability, and shelf life of avocados. This study investigates the efficacy of nitric oxide (NO) on postharvest physiology and quality of Booth 7 avocados treated with different concentrations of sodium nitroprusside (SNP) - a nitric oxide-releasing compound. Booth 7 avocados were immersed in SNP solutions (0.5 mM, 1.0 mM, and 1.5 mM), while the control fruit was immersed in distilled water for 15 min. After treatment, the fruit was stored at a temperature (T) of 8 ± 1 °C and relative humidity (RH) of 90 ± 5% for 35 days, during which the control fruit exhibited complete deterioration. The results revealed that Booth 7 avocados treated with 1.5 mM SNP concentration exhibited delayed quality changes during storage, reduced ethylene production and respiration rate, reduced alterations in soluble solids and acid content of the fruit flesh, as well as delayed changes in flesh and peel color. Additionally, the activity of total phenolic compounds (TPC), polygalacturonase (PG), and polyphenol oxidase (PPO) enzymes increased significantly, while the activity of the pectin methyl esterase (PME) enzyme was reduced. In conclusion, SNP treatment improved the quality and can be utilized as a potential postharvest preservative for Booth 7 avocados. For producers and distributors, the use of SNP in avocado postharvest management offers the potential to extend shelf life without compromising fruit quality.

Enhancement of antioxidant quality by Bacillus siamensis N-1 and the role of LcPOD4 in regulating peel browning and senescence of litchi fruit

Plant peroxidases (POD) are involved in various physiological and biochemical processes. Currently, there are relatively few studies on the role of POD in regulating the antioxidant capacity and senescence of postharvest litchi. In this study, we assessed the effects of Bacillus siamensis strain N-1 on the physiology and antioxidant quality of litchi fruit stored at 25 ℃, and characterized the molecular function of LcPOD4 gene in regulating the senescence of litchi fruit. The results showed that N-1 treatment significantly suppressed the increase in ethylene production, electrolyte leakage, and malondialdehyde (MDA) but did not inhibit the respiration rate of litchi during storage. Meanwhile, N-1-treated fruit maintained higher levels of phenolics, flavonoids, and total antioxidant capacity (T-AOC) and lower levels of superoxide anions (O2-.) and hydrogen peroxide (H2O2). In addition, N-1 treatment enhanced the activity of defense enzymes, including superoxide dismutase (SOD), peroxidase (POD), glutathione reductase (GR), and phenylalanine ammonia-lyase (PAL). The results of quantitative real-time PCR (qRT-PCR) showed that the expression of nine selected LcPOD genes was induced by N-1 treatment at later stages of litchi storage. LcPOD4 cloned from litchi fruit was located in the cell wall and membrane. Transient overexpression of the LcPOD4 gene in tomato and litchi fruits significantly enhanced POD activity and total phenolic and flavonoid contents while accelerating peel color change in the fruit. Collectively, our results indicate that LcPOD4 may contribute, at least partially, to the enhancement of antioxidant capacity in litchi fruit but does not retard peel browning and senescence.

Phenyllactic acid treatment for controlling anthracnose disease (Colletotrichum musae) and preserving banana fruit quality during storage

Banana is considered climacteric fruit that undergoes rapid post-harvest senescence, making it highly susceptible to diseases such as anthracnose, leading to a decline in quality. To address this issue, researchers investigated the effects of phenyllactic acid (PLA), a novel natural bio-preservative with broad-spectrum antibacterial properties, on banana fruit after harvesting. The study revealed that PLA treatment resulted in improved attributes of postharvest quality, including reduced changes in peel color, soluble solids concentration, and firmness. Additionally, respiratory rate, ethylene release, and disease index were significantly decreased, indicating that the fruit's physiological processes were better regulated. Furthermore, PLA treatment enhanced the activity of disease-resistant enzymes β-1,3-glucanase and chitinase, and upregulated the expression of pathogenesis-related genes. Importantly, PLA demonstrated its efficacy in suppressing the growth of anthracnose-causing fungi (Colletotrichum musae) and reducing disease severity on harvested fruit. In conclusion, PLA treatment shows promise as a new approach to maintain the freshness and quality of harvested banana fruit by reducing disease development, regulating physiological processes, and enhancing disease resistance mechanisms.

Changes in Physicochemical Characteristics, Peel Color, and Juice Attributes of ‘Moro’ Blood Orange Fruit Treated with Glycine Betaine and Methyl Salicylate during Cold Quarantine Storage

Cold quarantine storage is the practice of subjecting citrus fruit to low temperatures after harvesting to comply with stringent international phytosanitary standards for export, but fruit quality can be affected during storage. Therefore, this study investigated the effects of glycine betaine (GB) and/or methyl salicylate (MeSA) on physicochemical changes, chemical attributes of juice, and peel color of ‘Moro’ blood orange at cold quarantine storage (2 °C) for 60 days. Fruit were treated with GB (15 and 30 mM) by vacuum infiltration at 30 kPa for 8 min and vapor treatment of MeSA (100 µM) for 18 h as well as the combination of both GB concentrations with MeSA. The key findings of this research revealed that the combined treatment of 30 mM GB and 100 µM MeSA significantly mitigated weight and firmness losses in ‘Moro’ blood orange fruit during the cold quarantine period. Furthermore, there was a decrease in titratable acidity (TA) across all treatments, with the highest TA recorded for the 30 mM GB + 100 µM MeSA combination. Conversely, total soluble solids (TSS), TSS/TA ratio, and juice pH increased in all treatments, with the control treatment displaying the highest values. Regarding peel color parameters, which encompass L* (lightness), b*, hue angle (h°), chroma (C*), and a*, as well as the citrus color index (CCI), these exhibited characteristic changes during cold quarantine storage. However, the application of GB and MeSA, especially at the 30 mM GB + 100 µM MeSA level, noticeably delayed these peel color variations. Overall, GB and MeSA treatments offer significant advantages in preserving the physicochemical characteristics and chemical attributes of ‘Moro’ blood oranges during cold quarantine storage. These findings underscore the potential of GB and MeSA treatments for maintaining the quality of ‘Moro’ blood oranges during cold quarantine storage, with a noteworthy synergistic effect between MeSA and GB in preserving fruit quality.

Application of exogenous cytokinin regulates cytokinin oxidase and antioxidant activity to maintain chlorophyll pigment during ripening of banana fruit

Banana fruit ripening is accompanied by changes in activity of chlorophyll degradation. Herein, the application of exogenous cytokinin of forchlorfenuron (CPPU) to delay the ripening process by retarding degradation of chlorophyll was investigated. The changes in peel color, hue angle, chlorophyll fluorescence, and chlorophyll content were significantly inhibited by exogenous application of cytokinin. Content of endogenous cytokinin of t-zeatin was maintained and the increase of cytokinin oxidase (CKX) activity was retarded. Similar change trends were verified in the isolated peel tissues treated with CPPU. Relative expression level of the genes involved in cytokinin synthesis (MaIPT1/12) were upregulated, and CKX-related (MaCKX1/12) and chlorophyll degradation-related catabolism (MaPAO1, MaCLH1, MaSGR1, MaRCCR1, and MaRCCR12) were downregulated during storage. In addition, the scavenging activity of free radicals and membrane integrity were stabilized. Application of exogenous cytokinin of CPPU was proposed to competitively inhibit CKX activity to maintain endogenous cytokinin level, which further delayed chlorophyll degradation during banana fruit ripening.

CaCl2 treatment effectively delays postharvest senescence of passion fruit.

This study aimed to systematically investigate the changes in peel color, physicochemical characteristics, textural properties, and peel ultrastructure between CaCl2-treated and water-soaked passion fruit under short-term storage at room temperature (20°C) for eight days. The fruit peel was further analyzed and compared for the differences in calmodulin (CaM) gene expression between the two groups. The data were analyzed using principal component analysis. The results confirmed that CaCl2 treatment effectively maintained the appearance and color of passion fruit, inhibited peel browning, and improved fruit quality. The treatment had an effect on maintaining the physiological properties of passion fruit parenchyma, effectively delayed the passion fruit senescence, and kept the structural integrity of the fruit peel. The relative expression of PeCaM gene in the CaCl2-treated fruit peels was higher than that of the control peels. The Ca2+ stimulated the relative expression of the PeCaM gene, which delayed the senescence of passion fruit.

Change in Peel Color of Guava Fruit (Psidium guajava L.) ‘Crystals’ During Storage

Change in Peel Color of Guava Fruit (Psidium guajava L.) ‘Crystals’ During Storage

Transcriptomic analysis in tomato fruit reveals divergences in genes involved in cold stress response and fruit ripening.

Cold storage is widely used to extend the postharvest life of most horticultural crops, including tomatoes, but this practice triggers cold stress and leads to the development of undesirable chilling injury (CI) symptoms. The underlying mechanisms of cold stress response and CI development in fruits remain unclear as they are often intermingled with fruit ripening changes. To gain insight into cold responses in fruits, we examined the effect of the potent ethylene signaling inhibitor 1-methylcyclopropene (1-MCP) on fruit ripening, CI occurrence and gene expression in mature green tomatoes during storage at 20°C and 5°C. 1-MCP treatments effectively inhibited ethylene production and peel color changes during storage at 20°C. Storage at 5°C also inhibited both ethylene production and peel color change; during rewarming at 20°C, 1-MCP treatments inhibited peel color change but failed to inhibit ethylene production. Furthermore, fruits stored at 5°C for 14 d developed CI symptoms (surface pitting and decay) during the rewarming period at 20°C regardless of 1-MCP treatment. Subsequent RNA-Seq analysis revealed that cold stress triggers a large-scale transcriptomic adjustment, as noticeably more genes were differentially expressed at 5°C (8,406) than at 20°C (4,814). More importantly, we have found some important divergences among genes involved in fruit ripening (up- or down-regulated at 20°C; inhibited by 1-MCP treatment) and those involved in cold stress (up- or down-regulated at 5°C; unaffected by 1-MCP treatment). Transcriptomic adjustments unique to cold stress response were associated with ribosome biogenesis, NcRNA metabolism, DNA methylation, chromatin formation/remodeling, and alternative splicing events. These data should foster further research into cold stress response mechanisms in fruits with the ultimate aim of improving tolerance to low temperature and reduction of CI symptoms during cold storage.

Influence of long-distance air transport conditions on horticultural product quality: Case study of fresh mango shipment from Thailand to France

Four instrumented boxes of mangoes Mangifera indica L. cv. “Nam Dok Mai” were shipped from Bangkok, Thailand, to Paris, France, without control of the boxes’ positions on the aircraft. Two boxes were shipped via a direct flight and two boxes were shipped via an indirect flight. For each box, the internal air temperature, the external air temperature and relative humidity and surface temperature of two fruits were recorded throughout the supply chain from a packing house in Thailand to a storage room in France. A maximum fruit temperature of 33 °C (during transport from an orchard to the packing house) and a minimum fruit temperature of 8 °C (in a cold room of the logistics company following arrival at the airport in France via the indirect flight) were observed. The slight temperature difference between the air and the fruit surface temperature (< 1 °C on average) for both direct and indirect flights suggests that the air was stagnant inside the box and, thus conduction was the main heat transfer mode. Models of product temperature, mass loss, and peel color changes throughout the supply chain were developed. The numerical and the experimental values were in good agreement. These models were able to predict the product mass loss and peel color evolution as a function of a supply chain scenario.

Antioxidant response and quality of sunburn Beurré D'Anjou pears (Pyrus communis L.)

Sunburn is a physiological fruit disorder induced by exposure to excessive solar radiation. This disorder leads to significant losses in the yield of marketable fruits by negatively affecting quality parameters such as maturity and external color of the fruits. The purpose of this work was to characterize the physiological and biochemical aspects related to oxidative metabolism in Beurré D'Anjou pear fruit with different sunburn levels. Fruits were collected and classified into three sunburn levels at harvest: no sunburn (S0), mild sunburn (S1), and moderate sunburn (S2). On sunburned area, the maturity indices were measured on the fruit flesh, while external color, photosynthetic and photoprotective pigments, total phenols, electrolyte leakage, lipid peroxidation, antioxidant capacity and antioxidant enzymatic activities were determined on fruit peel. The hue angle and saturation of peel color of pears with different sunburn levels showed significant reduction with increasing damage. These changes in peel color were associated with a reduction in chlorophyll content and variations in carotenoid and anthocyanin levels. Due to metabolic changes resulting from defense and adaptive responses to high solar radiation, sunburned tissues showed significantly increased firmness, soluble solids content, and starch degradation, and lower acidity compared to undamaged fruits. We observed also increased antioxidant capacity in the peel of S1 and S2 fruit, related to higher phenolic contents and increased SOD and APX activities. Consistent with previous reports in apple, our study demonstrates that sunburn affects pear fruit quality traits and maturity state by enhancing oxidative metabolism.

The impact of alginate composites enriched with spent black tea, green tea, jasmine tea, and Oolong tea wastes on the shelf-life extension of fruits and vegetables

Bananas and tomatoes are of the most valuable staple foods in the world. They are widely cultivated in tropical countries. Freshly harvested green bananas and tomatoes are brought from the plantation field, packed and shipped to many countries such as the USA and European countries. However, being climacteric fruits, a major challenge for bananas and tomatoes supply stakeholders is the short post-harvest shelf-life due to rapid onset of ripening and undesirable ripening-associated changes, which result in their major losses. This work aimed to determine the impact of biocomposites based on spent tea waste (STW) and alginate on Cavendish banana (Musa acuminata) and tomatoes shelf-life. STW from black tea, green tea, jasmine tea, and Oolong tea were obtained through hot water extraction. The highest and lowest recoveries were recorded for green tea powder (96.0%) and Oolong tea leaf (88.33%), respectively. Composites were fabricated in sodium alginate cross-linked calcium chloride with or without STW. The STW-alginate composites were investigated for their effects on water absorptivity, gas absorptivity, and ripening of mature green bananas and tomatoes via monitoring of peel color changes visually and comparing to the standard color charts. The results indicated that the STW-alginate composites had variable effects on water absorptivity compared to the control. The spent green tea powder-alginate composite displayed the highest water absorptivity (212%). Moreover, the STW-alginate composites were able to prolong the ripening of both bananas and tomatoes stored in both plastic containers and modified atmosphere storage (MAP) bags at room temperature compared to the control. Composite enriched with spent green tea retained banana greenness for up to seven weeks compared to less than three weeks for the control. The results were consistent for follow-up study using MAP bags with banana and tomato. Specifically, compared to controlled group, green tea powder followed by Jasmine tea powder were the only two composites could extend to six weeks. Accordingly, STW-alginate composites hold potential as simple and novel bio-sorbents that can be applied in extending post-harvest banana shelf-life in a safe and sustainable manner.

Non-destructive determination of ripening in melon fruit using time-resolved spectroscopy

The aim of this work was to explore the feasibility of time-resolved reflectance spectroscopy (TRS) in determining the ripening degree and the quality of orange-fleshed melons. Sixty ‘Honey Moon’ melons were measured by TRS in the 540-1064 nm range and classified as less (LeM), medium (MeM), and more (MoM) mature according to increasing values of μa540. MoM fruit showed yellower peel color, slightly more orange pulp, higher juiciness and higher carotenoid contents than LeM ones. MoM fruit also showed higher internal ethylene concentration and lower firmness than LeM ones, even if the differences were not significant. The μa540 was positively related to internal ethylene, carotenoid accumulation, and juiciness, indicating that μa540 was linked to different ripening processes in melons. However, the relationship between μa540 and total carotenoid content was not as high as expected due to the low variability of pulp color and of carotenoid content. Changes in flesh color toward a more orange shade were accompanied by increased juiciness and ethylene production and by carotenoid accumulation, while changes in peel color were associated with changes in flesh firmness and juiciness. In conclusion, the absorption coefficient measured at 540 nm (μa540) by TRS could be used to sort melons in different ripening degrees; however, its applicability will need to be evaluated on a larger number of fruits and on other varieties.

Unveiling the molecular mechanism involving anthocyanins in pineapple peel discoloration during fruit maturation

Peel color is a key factor that affects the fruit’s aesthetic and economic values. Limited knowledge is available on the regulation of pineapple peel discoloration. Here, we report that a decrease in anthocyanin biosynthesis, particularly cyanidin, is predominantly associated with the pineapple peel color change during maturation. The findings suggest that the changes in the expression of key structural genes (early and late biosynthetic genes) of the anthocyanin (cyanidin) biosynthesis pathway are responsible for peel discoloration. Based on a gene co-expression analysis and a transient expression, two transcription factors i.e., AcHOX21 and AcMYB12, were identified, whose’ downregulation leads to reduced anthocyanin accumulation with fruit maturation. The endogenous levels of jasmonic acid, gibberellic acid, and auxins are also involved in anthocyanin-content-led peel discoloration. Overall, the discovery of genes regulating anthocyanin biosynthesis in pineapple peel provides a theoretical basis for improving the fruit’s aesthetic value through genetic engineering.

A mango biological fingerprint anti-counterfeiting method based on Fuzzy C-means clustering

The anti-counterfeiting of agricultural products plays an important role in protecting the rights and interests of consumers and maintaining the healthy development of the food market. Traditional anti-counterfeiting technology mainly relies on anti-counterfeiting features of packaging or labeling, which has the risk of being copied and reused. Biological fingerprint anti-counterfeiting is a method of anti-counterfeiting that takes the biological fingerprint of agricultural products as the anti-counterfeiting feature. This paper aims to take the distribution of lenticels on the surface of mango as a biological fingerprint, and propose a mango biological fingerprint anti-counterfeiting method. As the mango ripens, the peel color of mango will change significantly, which will affect the accuracy of anti-counterfeiting identification. In this paper, the images of ripe mangoes are classified by Fuzzy C-means clustering, and appropriate image enhancement technology is used to highlight the features. The results show that the mango biological fingerprint anti-counterfeiting method based on Fuzzy C-means clustering has good accuracy and robustness, and effectively reduces the impact of peel color change on anti-counterfeiting identification during mango ripening. These results support that it is feasible to use the lenticels distribution of mango as a biological fingerprint. In this paper, a computer vision anti-counterfeiting method based on lenticels distribution is proposed.

A Systematic Approach of Formulating Chitosan– Nanosilica Coating for Mango (Mangifera indica L. ‘Carabao’) Fruit

The application of fruit coatings reduces gas exchange between the environment and the fruit by creating additional layer to the fruit’s surface. If there is insufficient gas exchange, fruit coatings could induce anaerobic respiration and physiological disorders. Chitosan (CS) and nanosilica (NS) composite coatings for fresh ‘Carabao’ mango fruits were developed by calculating the required oxygen (O2) transmission rate of the coating given the fruit’s respiration rate, surface area and mass. To maintain the respiration requirements of the fruit, computed O2 transmission rates of the coating material should be equal or higher to 0.3270 mL∙cm-2 ∙hr-1 , 0.4530 mL∙cm-2 ∙hr-1 and 0.9608 mL∙cm-2 ∙hr-1 , at 15°C, 20°C and 25°C, respectively. At all temperature regimes, 0.75% CS has higher O2 transmission rate (0.814 mL∙cm-2 ∙hr-1 , 0.935 mL∙cm-2 ∙hr-1 , 1.136 mL∙cm-2 ∙hr-1 ) than 1% CS (0.450 mL∙cm-2 ∙hr-1 , 0.582 mL∙cm-2 ∙hr-1 , and 0.595 mL∙cm-2 ∙hr-1 ). Subsequent laboratory trials using 0.75% CS for mango at 20°C showed that the fruit coating could slow down weight loss and retard the peel color change for five days when compared to the uncoated fruits. Sensory tests in terms of color, taste, flavor, and aroma showed that the coated fruits are acceptable and of comparable quality as the control. Fruits coated with 1% CS exhibited delayed peel color change and weight loss but have symptoms of anaerobic respiration and acetaldehyde formation.

Proanthocyanidin delays litchi peel browning by inhibiting ethylene biosynthesis, respiratory metabolism, and phenol oxidase activities

Proanthocyanidin (PA) promotes antioxidant capacity and enhances resistance against oxidative stress-induced senescence in fruits after harvest. However, the effects of PA on the postharvest physiology of litchi fruit remain unclear. This study aimed to determine the effect of PA on ethylene and respiration physiology, and on browning enzymes of ‘feizixiao’ litchi stored at 25 °C for 8 d. Proanthocyanidin treatment delayed peel browning and color change, maintained higher peel lightness, and reduced ethylene production and respiration rates in litchi fruit. Subsequently, the key genes and/or enzymes involved in the ethylene biosynthesis pathway and respiration metabolism were determined. The PA-treated fruit exhibited lower levels of 1-aminocyclopropanecarboxylic acid (ACC) content, ACC synthase (ACS) and ACC oxidase (ACO) activity, and an inhibition of LcACS7/9 and LcACO1/2 genes on the peel and pulp compared to that of the control. In addition, the application of PA reduced respiration rate by downregulating the expression of LcAtpB, LcAOX1, LcUCP1, LcAAC1, and LcSnRK2. Furthermore, the phenol oxidase including peroxidase (POD), polyphenol oxidase (PPO), and laccase (LAC), were inhibited during litchi peel browning and senescence. Therefore, the process of PA-delayed browning of litchi may occur by delaying ethylene production and respiratory rate and inhibiting phenol oxidase activities in litchi fruit.

Carboxymethyl cellulose coating regulates cell wall polysaccharides disassembly and delays ripening of harvested banana fruit

Banana is a perishable fruit that ripens and deteriorates quickly after harvest. In this work, we investigated the impact of a dip in carboxymethyl cellulose (CMC) at concentrations of 0.5%, 1.0% and 1.5% on the quality of harvested bananas during storage at ambient conditions of 20 ± 1 ºC for a 15-d period. It was noted that 1.5% CMC markedly delayed the occurrence of decay incidence (9%) and suppressed physiological weight loss (6%). The 1.5% CMC treatment suppressed the activities of chlorophyllase, pheophytinase, Mg-dechelatase and chlorophyll (Chl)-degrading peroxidase (POD), which ultimately delayed banana peel color changes by conserving higher total Chl contents and reducing the accumulation of carotenoids. This subsequently resulted in higher L* and a* along with a lower increase in b* values as compared with control. Banana fruit coated with 1.5% CMC exhibited delayed ethylene and respiration peaks in comparison with control. In the same way, 1.5% coating maintained higher firmness and showed higher contents of protopectin, chelate-soluble pectin, sodium carbonate soluble pectin, cellulose and hemicellulose along with lower water-soluble pectin due to reduced activities of cellulase, pectin methylesterase, polygalacturonase and β-glucosidase. In the same way, postharvest application of 1.5% CMC coating suppressed the increase in total soluble solids (TSS) and showed higher titratable acidity (TA) along with a lower ripening index (TSS/TA ratio) in flesh of banana fruit compared with control. In conclusion, 1.5% CMC application could be an appropriate coating concentration to delay the ripening and rapid softening of harvested bananas stored in ambient conditions.