Effect of cold‐shock treatment on chilling injury in mango (Mangifera indica L. cv. ‘Wacheng’) fruit

To investigate how cold shock may affect chilling injury in mango fruit (Mangifera indica L. cv. ‘Wacheng’), the fruit were treated for 3, 4 or 5 h at 0 °C, or treated for 8, 10 or 12 h at 4 °C, respectively, then transferred to 20 °C for 20 h prior to being stored at 2 °C, 85–95% RH. The chilling injury index of mango treated at 0 °C for 4 h was 59.7% lower than that of the control fruit directly stored at 2 °C, 85–95% RH. Some attributes were assayed in the fruit treated at 0 °C for 4 h. Ion leakage of the cold‐shock fruit at 0 °C for 4 h was 16% or 10% lower than that of the control on day 9 or day 12 of storage, respectively. Malondialdehyde content of the cold‐shocked fruit was 70% or 50% lower than that of the control on day 6 or day 12 of storage at 2 °C, respectively. Activities of catalase, ascorbate peroxidase, and contents of glutathione and phenolic compounds in the fruit during storage were all markedly enhanced by the cold‐shock treatment, whereas activities of superoxide dismutase, glutathione reductase and content of ascorbic acid in the mango were slightly influenced by the cold‐shock treatment. These results suggest that cold‐shock treatment may hold promise as an alternative approach to reduce chilling injury in mango fruit during cold storage. Copyright © 2006 Society of Chemical Industry     

Maturity‐dependent chilling tolerance regulated by the antioxidative capacity in postharvest cucumber (Cucumis sativus L.) fruits

BACKGROUND: The aim of the present study was to reveal the effect of fruit maturity on the chilling tolerance of cucumber (Cucumis sativus L.) fruit and the oxidative and antioxidative mechanisms involved. Chinese mini‐cucumber (cv. Hangcui‐1) fruits were harvested at four developmental stages: Immature (3–8 days after anthesis (DAA)), Mature (9–16 DAA), Breaker (17–22 DAA) and Yellow (35–40 DAA). All fruits were stored at 2 °C for 9 days and rewarmed at 20 °C for 2 days. RESULTS: The chilling injury index declined with advancing fruit maturity. High superoxide anion radical production rate and hydrogen peroxide content were observed in Immature fruits after cold storage and rewarming. Under chilling stress, superoxide dismutase showed an early response. Fruits at earlier maturity stages exhibited higher catalase, ascorbate peroxidase and monodehydroascorbate reductase activities and glutathione content as well as its redox state, and lower peroxidase, dehydroascorbate reductase and glutathione reductase activities and ascorbate content as well as its redox state. CONCLUSION: Fruits at the earlier developmental stage are more susceptible to chilling injury, which is related to increased oxidative stress. High peroxidase activity and ascorbate content and maintenance of the latter's redox state appear critical to the chilling tolerance of cucumber fruits at later developmental stages. © 2012 Society of Chemical Industry     

Reducing Chilling Injury of Loquat Fruit by Combined Treatment with Hot Air and Methyl Jasmonate

The effects of a combined treatment of hot air (HA, 38 °C for 6 h) and methyl jasmonate (MeJA, 16 μmol L^?1) on chilling injury, fruit quality, and physiological changes in loquat fruit stored at 1 °C were investigated. The results showed that treatment with HA or MeJA alone both significantly alleviated chilling injury in loquat fruit compared with the control, while their combination had the lowest level of chilling injury symptoms and highest quality. The activities of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and catalase were enhanced by the combination of HA and MeJA. In addition, the combined treatment significantly inhibited the activities of phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase, which resulted in lower lignin content. Highest level of polygalacturonase activity and water-soluble pectin content and lowest level of protopectin content were also observed in the combined treatment. These results suggested that the enhanced chilling tolerance by combination of HA and MeJA treatment in loquat fruit was related to the induction of antioxidant enzymes and the inhibition of lignin biosynthesis. The combination of HA and MeJA treatment could be a useful technique to alleviate chilling injury and maintain quality of loquat fruit during cold storage.     

高湿贮藏对青椒果实冷害和抗氧化活性的影响

为探究高湿贮藏对减轻青椒果实冷害的作用及其与抗氧化活性的关系,将青椒果实放置于4 ℃、相对湿度分别为96%～99%和70%～75%的干雾控湿高湿冷库和普通低湿冷库中贮存15 d,每3 d测定果实冷害、品质和抗氧化系统相关指标变化。结果表明,高湿贮藏可显著延缓青椒果实的冷害指数、相对电导率和质量损失率的上升及硬度的下降,保持较高的叶绿素、抗坏血酸、总酚和总黄酮含量。与低湿贮藏相比,高湿贮藏还可显著提高超氧化物歧化酶、过氧化氢酶、过氧化物酶和抗坏血酸过氧化物酶的活力,保持较高的1,1-二苯基-2-三硝基苯肼和羟自由基清除率,减少超氧阴离子和过氧化氢的积累。这些结果表明,高湿贮藏可维持青椒果实较高的抗氧化活性,从而抑制活性氧对青椒的伤害,减少果实冷害的发生。     

Maturity‐related chilling tolerance in mango fruit and the antioxidant capacity involved

BACKGROUND: In order to evaluate how effect of mature stage on the chilling tolerance of mangoes (Mangifera indica L. cv. ‘Zihua’) and the mechanism involved, the fruit were categorized into three stages of ripeness: Green (100% green fruit), Preyellow (10–20% yellow fruit) and Yellow (45–55% yellow fruit) after harvest and stored at 2 °C for 12 days and then incubated at 25 °C for 2 days for chilling injury (CI) development. RESULTS: CI index in Preyellow and Yellow fruit was significantly lower than that of the Green fruit, as a rapid increase in ion leakage was observed in the Green fruit. Activities of superoxide dismutase, catalase, ascorbate peroxidase and polyphenoloxidase of Preyellow and Yellow fruit were higher than those of the Green from day 6 to day 12 during cold storage. A lower content of malondialdehyde but higher levels of glutathione and ascorbic acid were maintained in Preyellow and Yellow fruit than that in Green fruit. CONCLUSION: These results suggested that stronger resistance of Preyellow and Yellow mangoes to CI compared to Green fruit was due to their higher antioxidant capacity involved in the tolerance to chilling temperature. Alleviating CI in mangoes during storage may be achieved by storing the fruit when skin colour is beginning to change to yellow from green. Copyright © 2008 Society of Chemical Industry     

甘氨酸甜菜碱处理对桃果实冷害及抗坏血酸-谷胱甘肽循环代谢的影响

以‘湖景蜜露’桃果实为试材,采用10 mmol/L甘氨酸甜菜碱浸泡处理,分析甘氨酸甜菜碱处理对（0±1）℃贮藏桃果实冷害及抗坏血酸-谷胱甘肽（ascorbic acid-glutathione,AsA-GSH）循环代谢的影响。结果表明：甘氨酸甜菜碱处理能显著抑制桃果实冷害的发生,延缓相对电导率、丙二醛含量和过氧化氢含量的增加,提高抗坏血酸过氧化物酶、单脱氢抗坏血酸还原酶、脱氢抗坏血酸还原酶、谷胱甘肽还原酶活力以及PpAPX、PpGR、PpMDHAR和PpDHAR基因的表达水平,维持较高的抗坏血酸和谷胱甘肽含量以及抗坏血酸/脱氢抗坏血酸、谷胱甘肽/氧化型谷胱甘肽比例。结论：外源甘氨酸甜菜碱处理能通过调节AsA-GSH循环系统,有效清除桃果实中过量积累的过氧化氢,缓解低温胁迫对细胞膜的氧化损伤,从而减轻桃果实的冷害症状。     

Soluble Sugar Content and Metabolism as Related to the Heat-Induced Chilling Tolerance of Loquat Fruit During Cold Storage

The effects of high-temperature, short-time hot air treatment (45 °C for 3 h) on soluble sugar metabolism and chilling tolerance in loquat fruit stored at 5 °C for 5 weeks were investigated. Heat treatment significantly reduced chilling severity, as evidenced by lower firmness and internal browning and higher levels of extractable juice. Meanwhile, this treatment accelerated the activities of acid invertase, neutral invertase, sucrose phosphate synthase and sucrose synthase during storage. However, sucrose degradation was predominant, which caused lower levels of sucrose and higher levels of glucose and fructose in the heat-treated group. In addition, the ascorbate acid content and the activities of ascorbate peroxidase and glutathione reductase in the heat-treated fruit were much higher than those in control fruit, resulting in lower levels of hydrogen peroxide (H₂O₂) and malondialdehyde and decreased membrane permeability as well as a higher unsaturated/saturated fatty acid ratio at the end of storage. Our results suggest that the increased levels of reducing sugars, especially those of glucose, may induce the ascorbate–glutathione cycle activity to scavenge for H₂O₂, whose content relates to the heat-induced chilling tolerance of loquat fruit.     

外源钙和钙调素拮抗剂对冷藏桃果实耐冷性的影响

以‘白凤’水蜜桃为试材,分别用外源钙（CaCl2）和钙调素拮抗剂三氟拉嗪（trifluoperazin,TFP）浸泡桃果实,以蒸馏水为对照,研究其对冷藏桃果实抗冷性的影响。结果表明：与对照组相比,CaCl2处理能有效减轻桃果实果心褐变程度,缓解冷害症状,降低相对电导率,降低丙二醛（malondialdehyde,MDA）、H2O2含量,降低超氧阴离子自由基（O2 － ·）产生速率以及脯氨酸脱氢酶（proline dehydrogenase,PDH）活力,提高活性氧代谢相关酶（超氧化物歧化酶（superoxide dismutase,SOD)、过氧化氢酶（catalase,CAT）、抗坏血酸过氧化物酶（ascorbate peroxidase,APX）、Δ1-吡咯啉-5-羧酸合成酶（Δ1-pyrroline-5-carboxylate synthetase,P5CS）、鸟氨酸氨基转移酶（ornithine δ-aminotransferase peroxidase,OAT）、谷胱甘肽还原酶（glutathione reductase,GR））活力;另外,CaCl2处理后的桃果实表现为较高的脯氨酸、VC和谷胱甘肽（glutathione,GSH）含量;而TFP处理后的桃果实冷藏特性与CaCl2处理组相反。这说明钙-钙调素（Ca2＋-CaM）复合体参与了采后桃果实抗冷性调控,Ca2＋浓度的增加能维持桃果实活性氧代谢平衡,减少低温胁迫下膜脂过氧化与损伤,增加渗透调节物质脯氨酸的积累,从而减少桃果实冷藏期间冷害的发生,保持果实营养品质,延长果实贮藏时间。     

Low‐temperature conditioning combined with methyl jasmonate treatment reduces chilling injury of peach fruit

BACKGROUND: Peaches are sensitive to low temperature and develop chilling injury (CI) symptoms during refrigerated storage. This CI reduces consumer acceptance of peaches and limits the potential postharvest market life of the fruit. To develop a suitable technique to reduce CI, the effect of a combination of low‐temperature conditioning (LTC) and methyl jasmonate (MJ) treatment on CI of peach fruit was investigated in this study. RESULTS: Freshly harvested firm‐mature peaches were treated with a combination of LTC at 10 or 20 °C and 1 µmol L^?1 MJ and then stored at 0 °C for 5 weeks. The fruits developed CI during storage, manifested as internal browning and flesh mealiness. The combined treatment significantly reduced these CI symptoms and maintained higher fruit quality. The activities of polyphenol oxidase and peroxidase were significantly inhibited while those of superoxide dismutase, catalase and ascorbate peroxidase were induced by the combined treatment. In addition, the activities of phenylalanine ammonia‐lyase and polygalacturonase and the level of total phenolics were enhanced by the combined treatment. CONCLUSION: The combination of LTC and MJ treatment could be a useful technique to reduce CI and maintain quality in peach fruit during cold storage. Copyright © 2009 Society of Chemical Industry     

Controlled and modified atmospheres influence chilling injury,fruit quality and antioxidative system of Japanese plums (Prunus salicina Lindell)

Our objective was to compare the effects of controlled atmosphere (CA) and modified atmosphere packaging (MAP) on fruit quality, chilling injury (CI) and pro‐ and antioxidative systems in ‘Blackamber’ Japanese plums. Matured fruit were stored for 5 and 8 weeks at 0–1 °C in normal air, CA‐1 (1% O₂ + 3% CO₂), CA‐2 (2.5% O₂ + 3% CO₂) and MAP (~10% O₂ and 3.8% CO₂). CA was more effective than MAP in retention of flesh firmness and titratable acidity during cold storage. Fruit stored in CA‐1 showed reduced CI and membrane lipid peroxidation after 5 and 8 weeks of cold storage. Low O₂ atmospheres appeared to limit the generation of reactive oxygen species (ROS) and their efficient scavenging through the concerted action of superoxide dismutase and peroxidase. The role of ascorbate–glutathione (AsA–GSH) cycle in the regulation of oxidative stress was also studied during and after storage in different atmospheres. In conclusion, optimum CA conditions delayed fruit ripening and CI through augmentation of antioxidative metabolism and suppression of oxidative processes.     

LeMAPK4 participated in cold‐induced ethylene production in tomato fruit

BACKGROUND: Mitogen‐activated protein kinase (MAPK, EC 2.7.11.24) cascade from several plant species has been shown to be activated during response to abiotic stress. Ethylene plays an important role in fruit tolerance to environmental stress. However, the mechanisms by which MAPK regulates defence systems in fruit and the relationship between MAPK and ethylene remain to be determined. RESULTS: MAPK inhibitor significantly decreased the chilling tolerance of tomato (Lycopersicon esculentum cv. Lichun) fruit during cold storage. Moreover, decreases in ethylene content, LeACS2 expression and activities of 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase (ACS, EC 4.4.1.14) and ACC oxidase (ACO, EC 1.14.17.4) due to MAPK inhibitor occurred within 24 h after cold treatment. Upon treatment with cold and ethephon, the ethylene content, activities of ACS and ACO and expression of LeACS2, LeACO1 and LeMAPK4 increased. CONCLUSION: The results showed the regulation of MAPK in ethylene biosynthesis to protect tomato fruit from cold stress. In addition, the participation of LeMAPK4 in cold‐induced ethylene biosynthesis in tomato fruit was indicated. © 2013 Society of Chemical Industry     

Effect of 1‐methylcyclopropene on anthracnose rot caused by Colletotrichum acutatum and disease resistance in loquat fruit

BACKGOUND: Loquat (Eriobotrya japonica Lindl.) fruit are susceptible to fungal decay during postharvest storage at ambient temperature. The control of postharvest diseases of loquat is based primarily on the use of synthetic fungicides. To look for an alternative method for disease control, we investigated the effect of 1‐methylcyclopropene (1‐MCP) on controlling anthracnose rot caused by Colletotrichum acutatum of loquat fruit. RESULTS: 1‐MCP treatment significantly reduced decay incidence of loquat fruit. The treatment markedly inhibited accumulation of superoxide radicals and hydrogen peroxide and maintained higher superoxide dismutase, catalase and ascorbate peroxidase. Meanwhile, 1‐MCP treatment induced higher activities of two defense‐related enzymes—chitinase and β‐1,3‐glucanase—during 6 days' storage. Furthermore, the treatment inhibited increases in fruit firmness and internal browning index, and maintained higher extractable juice rate, total soluble solids and titratable acidity contents, thereby delaying the development of senescence. CONCLUSION: 1‐MCP was effective in reducing decay and might have enhanced the disease resistance in loquat fruit by increasing chitinase and β‐1,3‐glucanase, and maintained natural resistance by delaying senescence development. Copyright © 2010 Society of Chemical Industry     

预冷方式对长枣保鲜效果的影响

为了探究不同预冷方式对长枣保鲜效果的影响,本实验采用真空、压差和冷库预冷处理长枣,分析（1±1）℃贮藏期间长枣品质及抗氧化酶活力的变化。结果表明,与未预冷相比,3 种预冷处理均抑制了长枣的质量损失和软化,维持了可溶性固形物含量、可滴定酸质量分数及抗坏血酸含量,延缓了丙二醛积累和细胞膜透性增加。同时,预冷处理通过提高抗坏血酸过氧化物酶、超氧化物歧化酶和过氧化氢酶活力增强了细胞抗氧化能力,延缓了果实的氧化褐变和衰老。其中,压差预冷与其他处理组相比,能更显著抑制丙二醛积累和细胞膜透性增加,抑制细胞膜脂质过氧化保护细胞结构,同时维持较高的抗氧化酶活力,抵御氧化胁迫,抑制褐变,从而维持较高的贮藏品质,保鲜效果更佳。主成分分析结果进一步证明,压差预冷处理长枣贮藏稳定性更高,保鲜效果优于真空预冷和冷库预冷。综上所述,压差预冷能够有效维持长枣贮藏品质,延缓成熟和衰老进程。     

采前喷施胺鲜酯对采后龙眼果实贮藏期间果皮活性氧代谢的影响

为研究采前喷施胺鲜酯对采后龙眼果实贮藏期间果皮活性氧代谢的影响,以‘福眼’龙眼为材料,在龙眼盛花期后70、90、110 d用10 mg/kg胺鲜酯喷施龙眼果实3 次,以蒸馏水喷施为对照,龙眼果实在盛花期后120 d采收,采后龙眼果实经过挑选、清洗和晾干后用0.015 mm厚的聚乙烯薄膜袋密封包装（每袋50 个）,在（28±1）℃、相对湿度85%条件下贮藏,贮藏期间每天取样测定果皮O2－·产生速率、丙二醛（malondialdehyde,MDA）含量、活性氧清除酶（超氧化物歧化酶（superoxidase dismutase,SOD）、过氧化氢酶（catalase,CAT）、抗坏血酸过氧化物酶（ascorbate peroxidase,APX）和谷胱甘肽还原酶（glutathione reductase,GR））活力、内源抗氧化物质（还原型抗坏血酸（ascorbic acid,AsA）和还原型谷胱甘肽（glutathione,GSH））含量及1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除率和总还原力的变化。结果发现：与对照果实对比,采前喷施胺鲜酯可提高采后龙眼果实贮藏期间果皮SOD、CAT、APX、GR等活性氧清除酶活力,延缓AsA和GSH含量的下降,保持较高DPPH自由基清除率和总还原力,降低O2－·产生速率和膜脂过氧化产物MDA含量。结论：采前喷施胺鲜酯增强采后龙眼果实耐贮性与其能有效降低采后龙眼果实贮藏期间果皮活性氧代谢有关。     

冷激处理减轻茄子冷害与活性氧代谢的关系

探讨了冷激处理减轻茄子低温贮藏期间冷害的作用及其与活性氧代谢的关系。茄子果实分别采用0 ℃冰水混合物浸泡处理10、20、30、40 min后于4 ℃贮藏15 d。结果表明：20 min冷激处理能显著降低茄子果实的冷害指数,延缓果肉的褐变,减轻冷害症状;可显著提高茄子果实中超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶的活力,抑制超氧阴离子及过氧化氢产生,保持较高的总酚含量和1,1-二苯基-2-三硝基苯肼自由基清除率,维持较低水平的丙二醛含量和细胞膜透性;还可提高茄子果实脯氨酸含量和可溶性糖质量分数。上述结果表明,冷激处理能维持果实活性氧代谢平衡和提高渗透调节物质含量,从而减轻膜脂过氧化作用,保护膜结构的完整性,进而延缓茄子果实冷害的发生。     

Effects of high voltage electric field on storage life and antioxidant capacity of whole pomegranate fruit

The objective of this study was to investigate the effects of high voltage electric field (HVEF) on the antioxidant system in stored pomegranate fruit. The experiments were conducted at cold storage for two months under three selected electric field levels (0, 1.5 and 3 kV/cm). Results showed that non-enzymatic antioxidant contents including phenols and ascorbic acid were better preserved by 1.5 kV/cm treatment than control after 60 days of storage. While the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) in pomegranate fruit were significantly enhanced with 1.5 kV/cm treatment compared to control, Guaiacol peroxidase (G-POX) levels in the control group increased steadily and were highest at the end of the storage. Although the results obtained from 3 kV/cm treatment were acceptable till the end of the first month, due to oxidative damage of reactive oxygen species (ROS) produced in response to HVEF stress, their results come close to the control group at the end of the second month. These data suggest that the optimum electric field intensity for enhancing antioxidant contents in stored pomegranate fruits was 1.5 kV/cm.     

Preconditioning treatment maintains taste characteristic perception of ripe ‘September Sun’ peach following cold storage

Preconditioning is a thermal treatment that consists in maintaining stone fruits immediately after harvest and prior to cold storage at 20 °C for 24–48 h in special chambers aimed to extend fruit market life reducing chilling injury symptoms. This work investigates whether preconditioned ‘September Sun’ peaches had better eating quality than control fruit. Commercially harvested peaches were preconditioned and transferred to cold storage for 12, 26 and 40 days and evaluated for sensory characteristic perception after a ripening period at 20 °C. Acceptability of preconditioned fruit was higher than control fruit during this 40‐day cold‐storage period. Preconditioned and control fruit were also segregated into two clusters by PCA analysis; preconditioned fruit clustered together and show association to acceptability, sweetness and juiciness, while the second cluster was associated with flesh texture, acidity and aroma, suggesting the positive effect of preconditioning on final fruit quality. Preconditioned fruit maintained their sensory characteristics longer than control fruit during this 40‐day cold‐storage period.     

Effect of high-voltage electrostatic field pretreatment on the antioxidant system in stored green mature tomatoes

BACKGROUND: High‐voltage electrostatic field (HVEF), as a feasible and non‐chemical technique, applied to food preservation is a new area of study. Our previous research suggested HVEF could maintain the quality of tomato in storage. The present article intensively investigated the effect of HVEF pretreatment on antioxidant system of green mature tomato in storage. RESULTS: Green mature tomatoes were exposed to negative (or positive) HVEF for 2 h at 20 °C and then stored for 24 days at 13 ± 1 °C, 85–90% relative humidity. The results indicated HVEF significantly reduced contents of O₂^? and H₂O₂ of tomato fruits during storage compared to the control. HVEF treatment also enhanced the activities of antioxidant enzymes including catalase, superoxide dismutase, ascorbate peroxidase and peroxidase. The contents of non‐enzyme antioxidant components including reduced glutathione, phenols and ascorbic acid also were increased by HVEF treatment. However, HVEF treatment did not increase the content of lycopene in tomato fruit. CONCLUSION: HVEF treatment could promote the antioxidant capacity of tomato fruits in storage. Further research is be highly recommended to understand the mechanisms improving the antioxidant capacity of tomato fruits by HVEF. Copyright © 2011 Society of Chemical Industry