Reduced Decay Incidence Research Articles

A New Strategy for Enhancing Postharvest Quality of Sweet Cherry: High-Voltage Electrostatic Field Improves the Physicochemical Properties and Fungal Community.

Sweet cherry has a short shelf life due to the occurrence of senescence and fungal infection after harvest. This study aimed to study the effects of high-voltage electrostatic field (HVEF) on the physicochemical properties and fungal composition of sweet cherry during cold storage. The experiments were conducted at 4 °C for 28 days and the quality indicators were determined every 7 days during the period of storage. The fungal composition on sweet cherry was determined using high-throughput sequencing. The results showed that HVEF could better maintain the total soluble solids and inhibit the respiration of cherries. The decay incidence in sweet cherries was decreased by HVEF during cold storage. High-throughput sequencing revealed that HVEF could alter the fungal community and increase the fungal diversity on sweet cherries. Compared with the control group, HVEF decreased the abundance of Alternaria and Cladosporium on sweet cherries, while Aureobasidium, as a nonpathogenic fungus, increased and became the dominant strain at the end of the storage period. In summary, HVEF can improve the physicochemical properties of sweet cherry by inhibiting respiration and can reduce decay incidence by inhibiting specific pathogenic fungi. HVEF is expected to become an efficient and promising technology for the preservation of fruit.

Influence of chitin nanofibers and gallic acid on physical-chemical and biological performances of chitosan-based films

In this work, chitosan films loaded with gallic acid and different content of chitin nanofibers were prepared and subjected to different characterization techniques. The results showed that the inclusion of gallic acid to chitosan films caused moderate decrease in water vapor permeability (by 29 %) and increased tensile strength of films (by 169 %) in comparison to the neat chitosan films. Furthermore, it was found that the addition of chitin nanofibers up to 30 % into chitosan/gallic acid films additionally improved tensile strength (by 474 %) and reduced plasticity of films (by 171 %), when compared to the chitosan/gallic acid films. Increased concentration of chitin nanofibers in films reduced the overall water vapor permeability of films by 51 %. In addition, gallic acid and chitin nanofibers had synergic effect on high chitosan film's antioxidant and antifungal activity toward Botrytis cinerea (both above 95 %). Finally, chitosan/gallic acid/chitin nanofibers films reduced decay incidence of strawberries, increased total soluble solid content, and promoted high production of some polyphenols during cold storage, in comparison to the control chitosan films and uncoated strawberry samples. Hence, these results suggest that chitosan/gallic acid/chitin nanofibers can present eco-sustainable approach for preservation of strawberries, giving them additional nutritional value.

Yarrowia lipolytica increased the activities of disease defense related enzymes and anti-fungal compounds in asparagus (Asparagus officinalis)

Fungal diseases pose significant threats to the production of asparagus, resulting in economic losses and decreased crop quality. The potential of the yeast Yarrowia lipolytica as a biocontrol agent against Fusarium proliferatum, a common pathogen of asparagus, was investigated in this study. The effects of Y. lipolytica treatment on decay incidence, disease index, and activities of major disease defense-related enzymes were investigated. In addition, we examined the levels of antifungal compounds such as total phenols, flavonoids, and lignin in asparagus plants exposed to Y. lipolytica. The results showed that Y. lipolytica treatment significantly reduced decay incidence and disease index caused by F. proliferatum when compared to the control group. Furthermore, Y. lipolytica-treated plants showed increased activity of disease defense-related enzymes, indicating that defense responses were activated. The activities of all evaluated enzymes were significantly higher in Y. lipolytica-treated asparagus, indicating an improved ability to combat fungal pathogens. Furthermore, Y. lipolytica treatment increased the content of antifungal compounds such as total phenols, flavonoids, and lignin, which are known to possess antimicrobial properties. These findings highlight the potential of Y. lipolytica as a biocontrol agent for fungal diseases in asparagus crops. The ability of Y. lipolytica to reduce disease incidence, boost disease defense-related enzymes, and increase antifungal compound content provides valuable insights into its efficacy as a natural and sustainable approach to disease management. However, further investigations are needed to optimize application methods and determine its efficacy under field conditions.

Avirulent Isolates of Penicillium chrysogenum to Control the Blue Mold of Apple Caused by P. expansum.

Blue mold is an economically significant postharvest disease of pome fruit that is primarily caused by Penicillium expansum. To manage this disease and sustain product quality, novel decay intervention strategies are needed that also maintain long-term efficacy. Biocontrol organisms and natural products are promising tools for managing postharvest diseases. Here, two Penicillium chrysogenum isolates, 404 and 413, were investigated as potential biocontrol agents against P. expansum in apple. Notably, 404 and 413 were non-pathogenic in apple, yet they grew vigorously in vitro when compared to the highly aggressive P. expansum R19 and Pe21 isolates. Whole-genome sequencing and species-specific barcoding identified both strains as P. chrysogenum. Each P. chrysogenum strain was inoculated in apple with the subsequent co-inoculation of R19 or Pe21 simultaneously, 3, or 7 days after prior inoculation with 404 or 413. The co-inoculation of these isolates showed reduced decay incidence and severity, with the most significant reduction from the longer establishment of P. chrysogenum. In vitro growth showed no antagonism between species, further suggesting competitive niche colonization as the mode of action for decay reduction. Both P. chrysogenum isolates had incomplete patulin gene clusters but tolerated patulin treatment. Finally, hygromycin resistance was observed for both P. chrysogenum isolates, yet they are not multiresistant to apple postharvest fungicides. Overall, we demonstrate the translative potential of P. chrysogenum to serve as an effective biocontrol agent against blue mold decay in apples, pending practical optimization and formulation.

Improving fresh strawberry shelf life and quality by using the fresh‐keeping paper embedded with oregano essential oil and tea polyphenols

SummaryThe short shelf life of fresh strawberries limits its marketing potential, despite its valuable economic and nutritional benefits. An environmentally friendly fresh‐keeping paper was prepared with oregano essential oil (OEO) and tea polyphenols (TP) and used in the storage of strawberries. Results showed that, during the late storage period, the TP and OEO fresh‐keeping paper treatments reduced malondialdehyde (MDA) content by 29.04% and 34.47%, respectively, compared with the control samples. The treatments also reduced decay incidence, weight loss, epidermal microorganisms and total anthocyanins content (TAC). Furthermore, the treatments reduce polyphenol oxidase (PPO) activity, delay the colour development and maintain better sensory attributes. Notably, OEO fresh‐keeping paper treatment not only increased the titratable acidity (TA) and total soluble solids (TSS) content but also improved the scavenging ability of reactive oxygen species by maintaining high levels of superoxide dismutase (SOD) and catalase (CAT) activity. These results demonstrated that fresh‐keeping paper treatment has the potential to extend the post‐harvest life of strawberries and improve their quality.

Quality assurance of postharvest grapes against Botrytis cinerea by terbinafine

Worldwide, fruit is an indispensable treasure house of nutrition for human beings, occupying a vital position of human diet. Postharvest fruit storage requires efficient antifungal agents to control Botrytis cinerea, which is a vital postharvest disease affecting fruit and leading to enormous losses. However, with the enormous abuse of existing antifungal drugs, the problem of drug-resistant fungi is imminent, making the controlling diseases caused by pathogenic fungi even more challenging. Drug repurposing is an efficient alternative method, we evaluated a well-known antifungal chemical, terbinafine, against the agricultural pathogen, B. cinerea in vitro, as a result, terbinafine showed strong antifungal activity. Furthermore, the in vivo antifungal activity of terbinafine was evaluated, the results showed that terbinafine could reduce the decay area on grapes. Terbinafine could disrupt the cell membrane integrity, increase cell membrane permeability, and eventual cell death of B. cinerea. In addition, terbinafine reduced decay incidence, and weight loss and maintained the soluble solids, titratable acidity, ascorbic acid, total phenolic, and malondialdehyde content during the storage period of grapes. Overall, terbinafine could be an antifungal preservative for postharvest table grapes fresh-keeping.Graphical abstract

Pre-harvest silicon spraying: Impact on decay, metabolism, and overall quality of ‘Galaxy’ apples after harvest and cold storage

New strategies to reduce apple decay and maintain fruit quality during postharvest with low environmental impact are crucial. Thus, we aimed to assess the effects of pre-harvest foliar silicon (Si) application on decay incidence, metabolism, and overall fruit quality of ‘Galaxy’ apples at harvest and after cold storage. The experiments were performed during four seasons in commercial orchards and stored in cold rooms, and the following treatments were evaluated: 0, 1.12, 2.24, and 3.36 g L−1 of foliar sodium silicate (SS) (2015-16 and 2017-18 seasons), 0, 1.68, and 3.36 g L−1 of foliar SS (2018-19 and 2019-20 seasons), and 0, 1.68, and 3.36 g L−1 of sodium metasilicate (2019-20 season). Upon being harvested, the fruit were kept in cold storage. Foliar Si treatment of ‘Galaxy’ apples did not reduce decay incidence and severity after cold storage, and in some cases, it increased decay incidence. Moreover, Si treatment did not increase physiological disorders such as russeting, bitter pit, flesh breakdown, and mealiness. In some periods, Si treatment enhanced ripening metabolism as supported by higher ethylene biosynthesis, ACC oxidase activity, and reduced flesh firmness. Therefore, foliar Si application does not provide benefits to ‘Galaxy’ apple decay control.

Evaluation of integrated ultrasound and CaCl2 in hydrocooling water on the quality of ‘Bing’, ‘Lapins’, and ‘Sweetheart’ cherries stored in modified atmosphere packaging

Sweet cherry is a highly perishable fruit with a short storage life. Although CaCl2 dips positively affect the quality of sweet cherries, traditional sanitizer (i.e. NaClO) in the cleaning step contributes to fruit oxidation. The primary purpose of this study was to evaluate whether integrated applications of a chemical-free sanitizing technology (ultrasound) and CaCl2 in hydrocooling water (0 °C) had the potential in improving the quality of ‘Bing’, ‘Lapins’, and ‘Sweetheart’ cherries either packing in polyethylene (PE) or modified atmosphere packaging (MAP) bags. Regardless of cultivar and packaging type, ultrasound showed a similar effect as NaClO on quality attributes, decay, and antioxidant compounds (i.e. DPPH free radicals scavenging capacity, ferric reducing antioxidant power (FRAP), total phenolics (TP), and total flavonoids (TF)). However, NaClO induced high rates of stem browning (SB) and pitting in ‘Bing’ and ‘Lapins’ cherries packed with PE and MAP bags. Fortunately, Ultrasound + MAP provided a greater benefit in reducing SB in ‘Bing’ cherries. Adding 22.5–90 mM CaCl2 to hydrocooling water effectively enhanced calcium (Ca) and chloride (Cl) uptake in ‘Bing’ and ‘Lapins’, but not in ‘Sweetheart’. The cubic model showed high correlations between applied CaCl2 concentrations and postharvest disorders. Furthermore, CaCl2 concentration at 22.5–45 mM had stronger effects on reducing pitting and retaining TP in all three cultivars, irrespective of packaging type. However, increasing the application of CaCl2 concentration to 90 mM caused salt injury. Ultrasound did not provide an additional effect in increasing Ca and Cl uptake when it was combined with 22.5 mM CaCl2. However, this combination treatment retained high FF and SPF in all three cultivars packed with PE or MAP bags. Additionally, CaCl2 + ultrasound + MAP further reduced decay incidence in ‘Bing’ and ‘Lapins’ cherries and maintained high TP in ‘Lapins’ and ‘Sweetheart’ cherries, compared to the CaCl2 + ultrasound + PE treatment. Overall, the ultrasound with 22.5 mM CaCl2 in hydrocooling water slowed down quality deterioration, delayed disorders development, and improved antioxidant metabolism in MAP cherries.

Preharvest sprays with sodium nitroprusside induce resistance in harvested muskmelon against the pink rot disease

Pink rot caused by Trichothecium roseum is an important postharvest disease of muskmelon, and caused very serious postharvest losses. In this study, sodium nitroprusside (SNP), an exogenous nitric oxide donor, was applied four times during fruit development to muskmelon. The effect of SNP sprays on pink rot in harvested fruit and the influence on the mechanism of antioxidant enzymes and the phenylpropanoid pathway were investigated. The results showed that SNP sprays significantly reduced decay incidence and lesion area of muskmelon inoculated with T. roseum. SNP sprays induced the production of H2O2 in fruit at harvest, maintained cell membrane integrity, and increased the activity of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase during storage. In addition, SNP sprays also increased the activity of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumaroyl-CoA ligase, and promoted the accumulation of total phenolic, flavonoid, and lignin content in harvested muskmelon at harvest and during storage. These results suggesting a new possible way of prevention of postharvest pathogens. Practical applications Muskmelon is an important cash crop in the world, due to its unique appearance and intrinsic quality. However, postharvest losses of the muskmelon fruit are serious. Pink rot caused by Trichothecium roseum is one of the main reasons for the postharvest losses of harvested muskmelon. SNP preharvest sprays effectively induced the resistance and reduced decay incidence and lesion area of muskmelon inoculated with T. roseum. Compared with the postharvest treatment, which involves complete exposure, preharvest sprays not only affects the fruit, but also other portions of the plants, which could indirectly affect fruit quality. In addition, the preharvest treatment operation is simple and convenient, and the control effect is better than the postharvest treatment. Therefore, this work may provide a new approach for the control of postharvest diseases of muskmelon.

Biocontrol potential of a broad-spectrum antifungal strain Bacillus amyloliquefaciens B4 for postharvest loquat fruit storage

Loquat fruit is a subtropical fruit with high commercial values in the international market, but it actually has a short postharvest life due to mechanical damage and microbial decay. Until now, there exist few appropriate storage methods or biocontrol agents to control postharvest diseases and prolong storage period of postharvest loquat fruit. Recently, by comparing twelve Bacillus strains with biocontrol activity, a potential Bacillus amyloliquefaciens B4 was found to be effective in controlling various pathogens of loquat fruit. The in vivo results displayed that the active constituent in B4 exerting antifungal activity was bacterium itself, rather than metabolites. Scanning electron microscope was applied to observe the interaction between B4 and pathogens, and bacterial colonization and site occupancy on postharvest loquat fruit appeared to be one of the reasons why B4 could inhibit growth of fungal pathogens. In brief, Bacillus amyloliquefaciens B4 tends to be the most broad-spectrum antifungal biological agent available so far against postharvest pathogens of loquat fruit. Furthermore, oral toxicity test results suggested Bacillus B4 is actually non-toxic, making it a really suitable biocontrol agent for postharvest loquat fruit. The treatment for loquat fruit with B4 resulted in a lower disease incidence, with only 62.5 % compared to all decayed in the untreated group 20 d after inoculation at 25 ℃. This study provides a promising biological agent to control diseases of postharvest loquat fruit and improves our understanding of the possible biocontrol mechanisms of the Bacillus strain.

Possibility of using leaf extracts of tree-of-heaven (Ailanthus altissima (Mill.) Swingle) for the postharvest quality preservation of fresh apricot fruits

This study was conducted to test the possibility of using leaf extracts of invasive weed tree-of-heaven (Ailanthus altissima (Mill.) Swingle) for the postharvest quality preservation of apricot (cv. ‘Şalak’) fruits. Two different doses of A. altissima leaf extracts (0.5% and 2.5%) with and without supplements (0.1% g Arabic gum, 0.05% citric acid, 0.05% potassium sorbate and 0.05% ascorbic acid) were tested. Results showed that the extracts of A. altissima leaves have strong ability to prevent weight loss, reduce decay incidence, protect visual quality, delay the occurrence of chilling injury, keep fruit firmness and delay the reduction in ascorbic acid content.

Physiological responses and quality attributes of muscadine grape (Vitis rotundifolia Michx) to CO2-enriched atmosphere storage

Abstract Muscadine grape (Vitis rotundifolia Michx) is a non-climacteric fruit that rapidly loses quality during storage. This study aimed to assess the effect of controlled atmosphere (CA) on quality parameters and muscadine grapes decay. Berries of two muscadine grape cultivars, Triumph, and Supreme, were stored at 4 °C with 95 % relative humidity in either regular air (AIR), regular CA (RCA) (6 % O2 + 10 % CO2), or CA with extreme CO2 level (ECA; 4 % O2 + 30 % CO2) for up to 42 d. Treated berries with either RCA or ECA provided better control of weight loss. Both CA treatments reduced decay incidence, but there was no decay in ECA berries after 42 d for both cultivars and no evidence of CO2 injury. The results showed that berry softening was significantly delayed by RCA and ECA, which had a lower ethylene production rate than berries exposed to AIR. Application of RCA and ECA also retained greater total antioxidant activity, total phenolic compounds, and firmness compared to AIR. These results demonstrate that maintaining CA conditions postharvest leads to improved preservation of compositional quality and delayed softening and decay of harvested muscadine grapes compared with AIR storage.

EFFECT OF PACKAGING TYPE AND PERFORATION RATE ON STORABILITY AND QUALITY OF COMMON BEANS PODS: - A- PHYSICAL PROPERTIES

Common bean (Phaseolus vulgaris L.) is one of the most important members of leguminous crops grown in Egypt for either local consumption or exportation. For highly respiring produce such as mushrooms, peas and broccoli, traditional films like LDPE. However, the micro- perforated films are special films which are expensive and not available everywhere. This experiment was carried out at Fruit Handling Department laboratories, Horticultural Research Institute. Snap bean pods were obtained from a private farm at Giza, at suitable maturity stage of marketing. Uniform pods and free from blemishes were selected for storage experiment. Pods were packed in perforated or non-perforated polyethylene and polypropylene bags (30 μm thickness, 15 × 25 cm size) and each bag had 250 g as one replicate. There were two perforation rates in addition normal perforation rate. All treatments were stored at 7°C and 90 - 95 % relative humidity for 7, 14, 21days. Pods physical properties were recorded during storage. A significant decrease in weight loss percentage was observed in all perforated and non-perforated treatments in comparison with normal perforation rate. The highest weight loss was associated with those stored in normal perforation rate compared with all the other treatments. While the lowest weight loss was associated with those stored in non-perforated treatment in comparison with all other treatments. On the other side, reducing perforation rate significantly reduced decay incidence of stored common beans compared with non-perforated and normal perforated bags. Common beans stored in the less perforation rate bags was associated with the less decay incidence during storage. However, there was no significant differences among these treatments. Also, these treatments significantly reduced deterioration rate in all other studied quality of common beans during storage. Moreover, it is clear that, although common bean pods packaged in polyethylene bags had quality parameter higher than those packaged in polypropylene bags during the two seasons, there was no significant differences among these treatments in these aspects. We can conclude that, reducing bag perforation rate well led to improve common beans storability and reduce its deterioration rate during storage.

Exogenous Melatonin Attenuates Post-Harvest Decay by Increasing Antioxidant Activity in Wax Apple (Syzygium samarangense).

Wax apple is one of the most popular tropical fruit but undergoes serious post-harvest decay during storage, transportation and marketing. Melatonin (MT) plays important roles in plant growth, development and stress responses. However, its function in post-harvest preservation of fruit remains largely unknown. In the present study, the physiological function and molecular mechanism of exogenous MT for post-harvest preservation were evaluated in wax apple fruit. Results showed that MT treatment remarkably reduced decay incidence and the accumulation of excess reactive oxygen species (ROS) but increased the activity of antioxidant enzymes, suggesting that exogenous MT alleviates the post-harvest decay of wax apple by regulating the balance between ROS production and antioxidant system. Meanwhile, the gene expression was analyzed by transcriptome confirmed by quantitative PCR. This study provides insights into the regulatory mechanism and proper application strategies for post-harvest preservation of wax apple and other fruits though melatonin manipulation.

Graduated Controlled Atmosphere: A Novel Approach to Increase "Duke" Blueberry Storage Life.

Blueberries (Vaccinium corymbosum L.) are highly valued for their health-promoting potential, yet they are extremely perishable. Controlled atmosphere (CA) strategies reduce blueberry respiratory metabolism, slowing down senescence. However, the sudden change of atmosphere could elicit a physical abiotic stress in the fruit, negatively affecting quality. We propose an innovative approach based on controlled graduation to slowly reach optimum gas storage conditions as an alternative to standard CA. For two consecutive seasons, “Duke” blueberries were subjected to four different storage conditions: control (air); standard CA (sudden exposure to 5 kPa O2 and 10 kPa CO2 across the experiment); GCA3 and GCA7 (gradually reaching 5 kPa O2 and 10 kPa CO2 in 3 and 7 days, respectively). Fruit were stored for 28 days at 0 ± 0.5°C. Real-time respirometry provided an in-depth insight to the respiratory response of blueberries to their gas environment. Blueberries subjected to the graduated application of CA (GCA) treatments had a lower steady-state respiration rate compared to control and standard CA fruit. This indicated a reduction in metabolic activity that positively impacted quality and storage life extension. For example, GCA3 and GCA7 blueberries had a 25% longer storage life when compared to control, based on reduced decay incidence. In addition, GCA fruit were 27% firmer than control and CA fruit after 28 days of cold storage. GCA3 had a positive effect on maintaining individual sugars concentrations throughout the experiment, and both GCA treatments maintained ascorbic acid content close to initial values compared to a decrease of 44% in the control fruit at the end of the experiment. This work provides a paradigm shift in how CA could be applied and a better understanding of blueberry physiology and postharvest behavior.

Preserving postharvest storage quality of fresh loquat fruits by using different bio-materials.

Loquat fruits are known to have high nutritional contents and phytochemicals which are attributed with its health benefits. However, its storage life is reported to be very limited which negatively affect its marketability and consumption. Present study aimed to investigate the influence of seven different bio-materials or the combination of bio-materials on the postharvest life and storage quality of loquat (Eriobotrya japonica Lindl.) fruits var. 'Morphitiki'. The tested bio-materials or the combinations of current works was (1) OFI-Oputia ficus-indica extract; (2) OFI + Ns-Oputia ficus-indica extract + Nigella sativa oil; (3) OFI + PEx-Oputia ficus-indica extract + propolis extract; (4) OFI + C-Oputia ficus-indica extract + cinnamon oil; (5) Ns-Nigella sativa oil; (6) PEx-propolis extract and (7) CcEx-Chrysanthemum coronarium flower extract. As expected, weight loss showed an increasing tendency during storage period. Results showed that all of the tested bio-materials were effective in maintaining the postharvest quality of loquat fruits by reducing weight loss, positively affecting fruit firmness, preventing fruit browning and reducing decay incidence. Results suggested that loquat fruits can be stored with an acceptable quality for up to 35days at 4 ± 1°C and 95% relative humidity conditions, when treated with 0.5% Nigella sativa oil (Ns) or 0.5% propolis extract (PEx).

Possible use of organic compounds on shelf life and quality properties of peeled pomegranate.

Pomegranate cultivar (“Ardestani”) peeled and packed in polyethylene containers and treated with different natural products. Two concentrations of Aloe vera gel (10 and 15%), two different levels of saffron petal extracts (10 and 20% V/V) and two concentrations of saffron style extract (0.1 and 1% V/V) and control in one storage condition (7°C and 85% RH) were the treatments that applied by a full factorial randomized method. We examined natural substances for their possible application in extending the shelf life of fresh‐cut horticultural products to find a new approach for packaging and exporting pomegranates. About 13.8% mass loss in the 12th day of storage occurred because of higher enzymatic activity and lower membrane resistance. Our results show that all treatments significantly reduced mass loss, and Aloe vera gel treatments combined with saffron petal extract were the best. Although all treatments decreased ion leakage, Aloe vera gel and saffron petal extract reduced it significantly. Ion leakage incidence of arils at day 12 was lower in Aloe vera gel and saffron petal extract treatment compare to control. Application of both saffron extracts on arils reduced decay incidence and chilling injury from 86.67% to 6.67% and 60% to 26.67%, respectively. Total acidity, soluble solids content, total phenol content, anthocyanin content, and antioxidant capacity of arils changed differently in different treatments, and saffron petal extract significantly was the best one and increased anthocyanin content, total phenol content, and antioxidant capacity in arils. The microbial contamination increased in more extended storage, although both saffron extracts were successfully suppressed mold and bacteria growth below acceptable limits in 14 days at 7°C.

Preharvest multiple sprays with sodium nitroprusside promote wound healing of harvested muskmelons by activation of phenylpropanoid metabolism

Muskmelons are susceptible to mechanical damage at harvest and subsequent postharvest handling before storage. The wounds provide an easy pathway for fungi to infect, leading to postharvest decay of fruit during storage. Wound healing is considered as a positive defense process, which can restrict the invasion of pathogens. In this study, muskmelon fruit (Cucumis melo cv. Manao) during growth were repeatedly sprayed with 0.5 mM sodium nitroprusside (SNP, a exogenous donor of nitric oxide (NO)) or 0.1 mM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO, a scavenger of NO), to test the effect of these preharvest treatments on wound healing of harvested muskmelon fruit. The results showed that SNP sprays reduced decay incidence and disease severity of harvested muskmelons inoculated with Trichothecium roseum. SNP also promoted the accumulation of suberin and lignin at wound sites through increasing phenylalanine ammonia lyase (PAL) activity and stimulating the accumulation in total phenolics, flavonoids and lignin. On the contrary, c-PTIO sprays enhanced decay incidence and disease severity of wounded inoculated fruit, while decreasing PAL activity, the content of total phenolics, flavonoids and lignin and reduced the accumulation of suberin and lignin at wound sites. The present results suggest that NO released by SNP sprays promote the wound healing and prevent disease development in harvested muskmelons by inducing increase in PAL activity, the contents of phenolics, flavonoids, suberin and lignin accumulation at wound sites.

Influence of Chitosan-Based Coatings with UV Irradiation on Quality of Strawberry Fruit During Cold Storage

The objective of this work was to determine the effects of UV-C and chitosan coatings, alone or in conjunction, on the quality of strawberry fruit during storage. The treated fruits were examined for weight loss, respiration rate, soluble solids content, titratable acidity, ascorbic acid contents, total anthocyanins, total phenolic contents, decay incidence and sensory analysis of strawberry fruit were investigated during cold storage 1±0.5°C and 90±5% RH for 15 days. The result showed that chitosan coating with UV-C irradiation could further reduce decay incidence of strawberry fruit, restrain increase of respiration rate and weight loss of strawberry fruit compared to other treatments. Moreover, the total anthocyanins and total phenolic contents were maintained at higher level, and the decrease of ascorbic acid was restricted during storage period. Likewise, sensory analysis results also showed the effectiveness of UV-C + chitosan treatment by retaining the quality of strawberry fruit. Control and individual UV-C treatment had similar effects on respiration rate and weight loss. The results showed that UV-C + chitosan treatment can be an effective method for enhancing the phytochemical content and delaying fruit senescence of strawberry fruit during cold storage.

Preharvest β-aminobutyric acid treatment alleviates postharvest deterioration of ‘Bluecrop’ highbush blueberry fruit during refrigerated storage

We examined the effect of preharvest β-aminobutyric acid (BABA) treatment on postharvest quality and the softening of ‘Bluecrop’ highbush blueberry fruit during postharvest refrigerated storage. Reddish purple-colored fruit on shrubs were treated with 20 mM BABA and harvested 7 days after treatment when they turned dark purple. The harvested fruit were stored in clear polyethylene terephthalate clamshells at 2 °C for up to 20 days. Preharvest BABA treatment significantly delayed color changes, enhanced individual soluble sugars and organic acids, and reduced decay incidence. BABA-treated fruit also retained higher skin firmness throughout the storage period. Cell wall materials, closely associated with fruit softening, were significantly higher in BABA-treated fruit than in control. Moreover, preharvest BABA treatment significantly enhanced fruit pectin content at harvest and reduced activities of polygalacturonase and endo-1,4-β-xylanase, although hemicellulose content was unchanged. These results suggest that preharvest BABA treatment alleviates the deterioration of postharvest quality in ‘Bluecrop’ highbush blueberry fruit including skin firmness during refrigerated storage.