The effect of delay between heat treatment and cold storage on alleviation of chilling injury in banana fruit

BACKGROUND: To understand the mechanisms leading to the enhanced chilling resistance of banana by hot‐water dipping (HWD, 52 °C for 3 min), we investigated the effect of a 0.5–24 h delay between HWD and cold storage on chilling resistance and the change related to the metabolism of reactive oxygen species (ROS). RESULTS: The HWD‐treated fruit with a delay of less than 6 h exhibited markedly less chilling injury than the non‐heated control fruit, while a delay more than 6 h resulted in significant loss in chilling resistance. Increased hydrogen peroxide content and rate of superoxide radical production were detected in the fruit at 0.5–1.5 h after HWD treatment, and the levels declined with a longer delay, which may be correlated with the enhanced gene expression levels of the gene coding for a ROS‐generating related enzyme, NADPH oxidase (MaNOX). Enhanced activities and gene expression of an ascorbate peroxidase (MaAPX) were recorded in the fruit at 1.5–6 h after the treatment, and after 6 h the ascorbate peroxidase levels decayed to the levels as the control fruit. The higher APX gene expression was maintained in the treated fruit with a 3 h delay during the subsequent cold storage at 7 °C, correlating with the enhanced chilling resistance. CONCLUSION: The HWD‐treated fruit left at ambient temperature up to 6 h prior to cold storage maintained the effect of heat treatment and transiently increased ROS content, and the ascorbate peroxidase activity that occurred 0.5–6 h after the treatment may be correlated with the elevated chilling resistance induced by HWD treatment. Copyright © 2012 Society of Chemical Industry     

Sugar metabolism in relation to chilling tolerance of loquat fruit

The relationship between chilling injury and sugar metabolism was investigated in loquat fruit stored at 1 °C for 35 days. No symptoms of chilling injury occurred in the fruit, of ‘Ninghaibai’ cultivar, during the whole storage whereas, in ‘Dahongpao’ fruit, severe chilling symptoms were observed after 20 days of storage at 1 °C. ‘Ninghaibai’ fruit had higher levels of glucose and fructose and higher activities of sucrose hydrolyzing enzymes, such as sucrose synthase-cleavage and invertase, than had ‘Dahongpao’. Furthermore, the chilling resistant ‘Ninghaibai’ fruit also showed higher activities of hexokinase and fructokinase, involved in hexose phoshorylation and sugar signal generation. These results suggest that the higher content of hexoses and activities of hexose sensors were likely part of the mechanism for chilling tolerance of loquat fruit.     

香蕉残次果及香蕉花上乳酸菌的筛选鉴定

从海南省五指山地区采集的香蕉残次果及香蕉花上分离得到12株疑似乳酸菌菌株,通过生理生化特性及分子生物学鉴定得到4株植物乳杆菌（Lactobacillus plantarum）,其中从香蕉残次果上分离得到三株编号为CG1、CG5、CG7,从香蕉花上分离得到一株编号为CH2。对比四株菌的产酸速率曲线和生长曲线,发现菌株CG1的产酸速率和生长速率均明显高于其他3株菌（P＜0.05）。     

热处理诱导枇杷果实抗冷性与组织保护酶系变化的关系

研究热处理对冷藏枇杷果实诱导抗冷性的影响效果.枇杷果实采后经38℃热处理15 h,然后在1～4℃下冷藏,测定分析贮藏期间果实冷害级别、出汁率和失重率、呼吸速率、丙二醛含量以及过氧化物酶(POD)、超氧化物岐化酶(SOD)、多酚氧化酶(PPO)、脂氧合酶(LOX)活性的变化.结果表明:热处理减轻了冷害的发生,提高了出汁率,降低了失重率和呼吸速率,减少了丙二醛的积累,提高了POD酶活性,在贮藏后期维持较高的SOD酶活性,并抑制PPO和LOX活性的增加.热处理能够提高枇杷果实抗冷性,减轻冷害症状的发生.     

Modified atmosphere packaging confers additional chilling tolerance on ethylene-inhibited cantaloupe Charentais melon fruit

Cantaloupe Charentais melon fruits are subject to chilling injury when stored at low temperatures, around 2 °C. Ethylene-suppressed cantaloupe Charentais melon, expressing a 1-aminocyclopropane-1-carboxylic acid (ACC)-oxidase gene in antisense orientation, showed strong, but not total, resistance to chilling injury, allowing an extended storage at low temperatures. Modified atmosphere packaging (MAP) is known to alleviate chilling injury symptoms in a variety of chilling-sensitive horticultural commodities. In the present work, we have compared the effects of MAP in non-retractile plastic film and storage in air on ethylene production, respiratory activity, development of chilling injury symptoms, water loss, ion leakage and accumulation of ethanol and acetaldehyde in wild-type and ethylene-suppressed melons, during storage at 2 °C and after re-warming at 22 °C. MAP reduced chilling injury and extended the postharvest life of wild-type fruit and conferred additional chilling resistance on ethylene-suppressed melons. Reduction of ethylene production and water loss are necessary to prevent chilling injury symptoms in melon.     

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     

Increase in low molecular size uronic acid in ripening banana fruit

Uronic acid soluble in ethanol/water (4:1 v/v) increased from 9 ± 1 mg kg^?1 fresh weight in pulp of unripe banana fruit. Musa (AAA Group, Cavendish subgroup) ‘Williams’, to 53 ± 13 mg kg^?1 fresh weight in fruit ripened for 13 days. This increase began within the first 2 days of ripening. Uronic acid soluble in phenol/acetic acid/water (2:1:1 w/v/v) increased from 15 ± 5 to 86 ± 17 mg kg^?1 fresh weight during the first 8 days of ripening, accompanied by a decrease in cell wall uronic acid from 10·2 ± 0·8 to 4·4 ± 0·4 g kg^?1 fresh weight. Most or all of the uronic acid in extracts of ripe pulp cochromatographed with monogalacturonic acid. The results were consistent with hydrolysis of cell wall polyuronides by exopolygalacturonase (EC 3.2.1.67).     

采后茉莉酸甲酯处理对桃果实青霉病及细胞壁降解酶的影响

以桃果实为试材,研究了采后不同浓度茉莉酸甲酯（Me JA）处理对损伤接种桃果实扩展青霉（Penicillium expansum）病斑扩展的影响,并分析了最佳浓度Me JA处理后桃果实细胞壁降解酶活性的变化。同时研究离体条件下Me JA对P.expansum菌丝生长和孢子萌发的影响。结果表明,100μmol/L Me JA对桃果实P.expansum的病斑抑制效果最好,并且显著（p≤0.05）抑制了菌丝生长和孢子萌发。100μmol/L Me JA处理明显抑制了桃果实多聚半乳糖醛酸酶（PG）、果胶甲酯酶（PME）、果胶甲基反式消除酶（PMTE）、多聚半乳糖醛酸反式消除酶（PGTE）和β-葡萄糖苷酶活性。由此表明,Me JA抑制桃果实青霉病的发生与延缓果实软化有关。      

High‐temperature conditioning induces chilling tolerance in mandarin fruit: a cell wall approach

BACKGROUND: High‐temperature conditioning (3 days at 37 °C and 95% relative humidity), which protects ‘Fortune’ mandarins from chilling injury (CI), manifested as pitting in the outer part of the peel (flavedo), was applied prior to cold storage (2 °C) in order to investigate the involvement of cell wall composition in the chilling tolerance of mandarins. RESULTS: Both low‐temperature storage and high‐temperature conditioning barely modified the alcohol‐insoluble substance (AIS) content or the degree of pectin esterification in the flavedo. Water‐soluble pectins (WSP) were higher in heat‐conditioned than in non‐conditioned fruits at the onset of CI. In addition, the heat‐conditioning treatment was able to increase chelator‐soluble pectins (CSP) after short cold storage periods. Covalently bound polyuronides in alkali‐soluble pectins (ASP) increased only in fruits with high incidence of CI. Cellulose and hemicellulose increased at 2 °C in both conditioned and non‐conditioned fruits, indicating that these polysaccharides may be altered by low temperature but are not related to chilling‐induced damage. CONCLUSION: High‐temperature conditioning may reduce chilling‐induced flavedo pitting in ‘Fortune’ mandarin fruit by maintaining normal levels of WSP and increasing putative sites for calcium bridge formation within the cell wall, but not by inducing changes in other matrix cell wall components. Copyright © 2012 Society of Chemical Industry     

复合有机酸保鲜剂(OAA-7)在香蕉保鲜中的应用研究

研究本实验室配制的复合有机酸保鲜剂(OAA-7)在"香芽蕉"中的应用效果,发现200 mg/kg OAA-7溶液浸润可以降低贮藏过程中香蕉的失重和腐烂,对抑制香蕉可溶性固形物、还原糖含量的上升,保持香蕉硬度也有一定的帮助,可以明显提高了香蕉的优果率.     

Fatty acid composition and antioxidant system in relation to susceptibility of loquat fruit to chilling injury

Two cultivars of loquat fruit with contrasting chilling resistance were stored at 1 °C for 35 days to investigate the relationship between chilling injury and fatty acid composition and its antioxidant system. No symptoms of chilling injury occurred in the fruit of ‘Qingzhong’ cultivar during the whole storage, whereas in ‘Fuyang’ fruit, chilling injury increased sharply after 21 days of storage at 1 °C. ‘Qingzhong’ fruit had lower levels of superoxide radical and H₂O₂, in addition to lower lipoxygenase activity, but higher membrane lipid unsaturation and higher activities of superoxide dismutase and catalase than ‘Fuyang’. Furthermore, the chilling resistant ‘Qingzhong’ fruit also showed higher activities of antioxidant enzymes involved in ascorbate–glutathione cycle and higher levels of ascorbate acid and reduced glutathione. These results suggest that the higher membrane lipid unsaturation and the more efficient antioxidant system were both beneficial in enhancing resistance of loquat fruit to chilling injury.     

Effects of heat treatment on internal browning and membrane fatty acid in loquat fruit in response to chilling stress

BACKGROUND: Chilling injury (CI) limits the storage period and shelf‐life of red‐fleshed loquat fruit (Eriobotrya japonica Lindl.), which leads to a remarkable loss after cold storage. To develop an effective technique to reduce CI, the effects of a 38 °C heat treatment in air for 5 h, plus storage at 1 °C for 35 days, on internal browning (IB) and membrane fatty acid composition of the loquat cv. Jiefangzhong were investigated. RESULTS: Heat treatment delayed the occurrence of IB and inhibited the increase of IB index in ‘Jiefangzhong’ loquat fruit. Heat treatment maintained lower levels of electrolyte leakage and malondialdehyde content, and inhibited the increases in phospholipase D and lipoxygenase activities compared with the control fruit. Meanwhile, heat treatment inhibited the increases in palmitic, stearic and oleic acid levels and delayed the decreases in linoleic and linolenic acid contents, thus maintaining higher unsaturated/saturated fatty acid ratio than the control. CONCLUSION: These results suggest that the reduction of IB in chilled loquat fruit by heat treatment might due to maintenance of membrane integrity and higher unsaturated/saturated fatty acid ratio. Copyright © 2010 Society of Chemical Industry     

Acetylsalicylic acid alleviates chilling injury of postharvest loquat (Eriobotrya japonica Lindl.) fruit

Loquat (Eriobotrya japonica Lindl. cv. Luoyangqing) is a chilling-sensitive fruit and therefore has a limited postharvest life. While fruit stored at 5 °C retained its acceptable quality after 39 days, fruit stored at 0 °C had chilling injury with the symptoms of tissue browning and lignification, decrease in percentage juice, increase in superoxide free radical production, electric conductivity and lignification enzyme activities, including phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), and guaiacol-peroxidase (G-POD). Such chilling injury symptoms became more severe after fruit were moved to 20 °C shelf life. A postharvest application of 1 mmol/L aqueous acetylsalicylic acid (ASA, a derivative of salicylic acid) to loquat fruit significantly alleviated chilling injury symptoms, inhibited accumulation of superoxide free radical, and reduced PAL, CAD, and G-POD activities. ASA treatment impairing the accumulation of superoxide free radical may prevent chilling injury and lignification in loquat.     

不同贮藏温度及时间对黄瓜果实冷害发生的影响

为了研究不同贮藏温度及贮藏时间对黄瓜果实冷害的影响规律,对0～20℃的贮藏温度下,在贮藏时间15d内的黄瓜果实的细胞膜电解质渗透率进行了系统测试。结果表明:黄瓜冷害的发生与贮藏温度及处理时间有关,而电解质渗透率的变化能很好地体现不同贮藏温度及时间下,黄瓜细胞组织受损程度及与冷害发生的关系。研究发现,0℃下的渗透率最高,渗透率变化最为明显,渗透率增量最大。表明贮藏温度越低,电解质渗透率变化越明显,出现跃变的时间越早,则黄瓜冷害发生得越早;随着贮藏时间的延长,细胞膜电解质渗透率随之增加,冷害随之加重。同时,适当的变温处理可以有效地缓解和抑制冷害的发生,延长贮藏期。