热空气处理对香蕉果实生理变化的影响

研究了热空气处理对‘大叶青’香蕉果皮色素含量、呼吸作用及乙烯释放的影响。结果表明：与对照相比,４５℃热空气处理１２ｍｉｎ可抑制香蕉果皮中叶绿素ａ的降解,对叶绿素ｂ与类胡萝卜素的变化影响不大。热空气处理果实的呼吸及乙烯释放高峰出现较迟且峰值较小,果皮细胞膜的完整性能保持得较好。     

热激处理及贮藏温度对水蜜桃果实生理生化变化的影响

研究了热空气处理和贮藏温度对水蜜桃硬度，果皮色泽，色素含量，呼吸作用。乙烯释放，脂肪氧合酶（LOX）与过氧化物酶（POD）活性的影响。结果表明：40℃热空气处理24小时可保持果实的硬度，抑制果皮中叶绿素的降解，推迟了呼吸高峰的出现，保持了细胞膜的完整性，热处理抑制了乙烯的释放，降低了LOX和POD活性。     

香蕉采后乙烯释放率和呼吸速率与后熟变化的研究

测定了香蕉、大蕉和粉蕉三个品种的采后乙烯释放率和呼吸速率变化。结果表明,在相同采后条件(20～25℃)下,乙烯释放高峰在呼吸高峰之前出现,香、大、粉蕉分别在采后第10、8、6天达到乙烯释放高峰;采后第12、11、9天出现呼吸高峰。跃变期间,果肉圆片浸出液电导率明显升高,膜透性增加,并持续到衰老后期。在可食期,香、大、粉蕉电导率值顺次为293.33、316.67、267.39μυ/cm。从跃变高峰直至跃变后期,淀粉迅速降解,蔗糖和还原糖积累;到软熟时,淀粉基本完全转化为可溶性糖。三个品种中,刚采收时,粉蕉的果肉淀粉含量>大蕉>香蕉;软熟期,粉蕉的总可溶性糖含量>大蕉>香蕉。本文对乙烯与呼吸的关系,后熟变化与品种差异等进行了讨论。     

苹果新品种瑞雪的贮藏特性研究

【目的】明确苹果新品种瑞雪(Malus domestica Borkh.‘Ruixue’)的采后贮藏特性,为其进一步推广提供参考。【方法】以陕西白水苹果试验站采摘的套袋瑞雪苹果为试验材料,设置低温(0±0.5)℃和常温(20±2)℃2个处理,研究其贮藏期间呼吸强度、乙烯释放速率、表面色泽、硬度和可溶性固形物、可滴定酸、维生素C含量的变化,以及病害发生情况。【结果】0℃贮藏能够较好地维持瑞雪苹果的水分、硬度和可溶性固形物、可滴定酸和维生素C含量,抑制果皮色泽变暗、变黄,呼吸高峰和乙烯高峰分别出现在贮藏后45 d和60 d,贮藏120 d之后,出现虎皮病。常温贮藏30 d之内,果实品质维持较好,30 d之后,果实营养物质流失严重,呼吸高峰和乙烯高峰分别出现在贮藏后20 d和50 d,常温贮藏期间,虎皮病、苦痘病、腐烂病发病严重,果柄褐变增多,果皮油腻化严重。【结论】瑞雪苹果在低温下的耐贮性较好,但贮藏120 d时,开始出现虎皮病。常温条件下瑞雪果实迅速老化,出现各种病害,建议20～30 d内及时销售食用。     

香蕉采后保鲜技术流程概述

香蕉是一种典型的呼吸跃变型水果。在采后成熟过程中会释放乙烯,出现呼吸高峰,并使果实内部组织发生一系列成熟与衰老的生理变化。淀粉降解、可溶性糖含量增长、果肉变软,皮色转黄,果实软熟,随后进入衰老期。病害、机械伤会促进果实生理后熟,使贮藏寿命缩短,严重地影响香蕉生产和贮运     

青梅果实采后的软化特性与色泽变化

以青佳品种为试材研究了青梅在25℃±1℃、相对湿度85%贮藏条件下果实采后软化特性及色泽变化。结果表明:采后6～8d,青梅果实呼吸强度和乙烯释放量均出现高峰,表明果实属于呼吸跃变型;采后6d内,果肉硬度和叶绿素含量迅速下降,膜相对透性迅速增大,果肉色泽急剧转黄,表明6d内青梅果实易快速软化和黄化,在常温下仅能保鲜5d左右。采后2～4d,多聚半乳糖醛酸酶(PG)、果胶甲酯酶(PME)和羧甲基纤维素酶(Cx)活性升高,这可能是果肉急剧软化的主要原因。     

1-MCP对常温贮藏‘红香酥’梨保鲜效果的影响

以‘红香酥’梨果实为试材,研究了常温(20℃)条件下,不同浓度1-MCP处理对果实呼吸强度、乙烯释放量、果实品质和果实腐烂及风味的影响。结果表明:与对照相比,1-MCP处理能明显抑制贮藏期间‘红香酥’果实呼吸强度和乙烯释放量;1-MCP处理能明显延缓‘红香酥’果皮转黄,提高果皮色泽和亮度,提高好果率,贮藏后期保持较好的果实品质和风味,延长贮藏期;1-MCP处理对‘红香酥’果实硬度的影响不明显。常温(20℃)条件下,经0.5μL/L和1.0μL/L 1-MCP处理,‘红香酥’贮藏期可延长12 d以上,果实商品价值好。     

石榴果实的采后生理和贮藏特性

本试验中的石榴果实呼吸比率较低,无呼吸高峰出现。根据果皮色泽、汁液色泽及成分的变化测定,它们产生的乙烯量很少,而且对各种外加乙烯处理无反应。二氧化碳和乙烯生产率随温度的增加而增长。在0和10℃间果实的呼吸商为3.4;10和20℃间为3.0;而20和30℃间则为2.3。在5℃或低于5℃下贮藏导致了果实冷害,并且冷害症状的严重程度随贮藏时间的增加温度下降(3.5℃以下)而增加。冷害症状(在果实移至20℃贮藏3天后变得愈加明显)包括果皮褐色化、表皮凹陷和对衰败组织敏感性的     

不同温度和乙烯利浓度对‘宝岛蕉’果实后熟及品质的影响

采用不同浓度乙烯利处理并分别在18℃和20℃下后熟,测定果实硬度,果皮颜色、膜透性和叶绿素,果肉可溶性固形物、可溶性糖、淀粉和维生素C含量等指标,研究温度、乙烯利浓度对‘宝岛蕉’果实后熟进程及品质的影响。结果表明:在适度范围内提高温度和乙烯利浓度均对‘宝岛蕉’后熟进程和品质有积极作用,使果实硬度下降、果皮膜透性增加,总叶绿素含量下降,颜色由绿转黄,果肉可溶性固形物和可溶性糖含量增加,淀粉和维生素C含量减少,达到食用品质;20℃与18℃相比,适当高温可促进可溶性固形物和可溶性糖含量的上升,加速淀粉的水解和维生素C的转化,从而促进‘宝岛蕉’果实的成熟,缩短后熟时间。     

1-甲基环丙烯处理对“金红”苹果采后生理和常温贮藏品质的影响

以"金红"苹果果实为试材,采用1.0μL·L~(-1)浓度的1-甲基环丙烯(1-MCP)处理果实,研究了常温(20±1)℃条件下,1-MCP处理对"金红"苹果果实采后生理和贮藏品质的影响。结果表明:与对照(CK,1-MCP处理浓度为0)相比,1.0μL·L~(-1) 1-MCP处理可有效抑制"金红"苹果常温贮藏期间果实呼吸强度和乙烯释放量,推迟或抑制果实呼吸高峰和乙烯释放高峰的出现,显著(P≤0.05)降低果实的乙醇和乙醛含量,减轻细胞膜的透性,降低果实腐烂率。并且1-MCP能有效抑制果皮返糖发亮和底色转黄,保持果皮红黄鲜艳度,明显抑制果实硬度、维生素C和可滴定酸含量的下降,较好维持贮藏中后期果实的SSC。采用1-MCP处理可以将"金红"苹果常温贮藏期从9～12 d延长到30 d,仍能保持较好的外观和内在品质。     

A novel postharvest UV-C treatment to reduce chilling injury (membrane damage,browning and chlorophyll degradation) in banana peel

To investigate the mode of action of UV-C to alleviate CI in banana. Banana [Musa (AAA group), Cavendish subgroup cv. Cavendish] fruits were treated with UV-C at dosages of 0.03 kJ m⁻² prior to storage at 8 or 25 °C. UV-C treatment reduced both the incidence and severity of banana fruits stored under low temperature. UV-C treatment reduced membrane damage indicated by lower activity of lipoxygenase (LOX) and malondialdehyde (MDA) content. In additions, the in vitro polyphenol oxidase (PPO) activity was activated when fruits were stored at CI temperature and UV-C treatment could inhibit the PPO activity. UV-C treatment also delayed yellowing and chlorophyll (Chl) degradation due to the inhibition of chlorophyllase and chl-degrading peroxidase activities. Furthermore, the reduction of ethylene production and respiration rate by UV-C treatment results in extended postharvest shelf life of banana. These finding suggest that the loss of cellular compartments in consequence of membrane degradation, combined with the increase of PPO activity, might contribute to the development of CI in banana peel. UV-C treatment may play an important role in maintained membrane integrity and inhibited PPO activity, reducing the severity of CI symptom and delayed ripening in banana. This novel technique may offer an advance in postharvest handling of bananas and other chilling-sensitive commodities in order to reduce postharvest losses resulting from CI.     

Physiological and biochemical studies on chilling-injury of banana

Storage of banana fruits at low temperature was unsuccessful due to chilling-injury. Titratable acidity and respiration of banana fruits remained lower at 5°C than at room temperature and accompanied the prevention of ripening and chilling-injury. Dopamine (3,4-dihydroxyphenylethylamine) was the only major phenolic constituent in banana peel; low temperature might induce its oxidation to dark coloured substances.     

Changes in antioxidants and fruit quality in hot water-treated ‘Hom Thong’ banana fruit during storage

The effects of hot water treatment on antioxidants and fruit quality were investigated in banana fruit of cv. Gros Michel (Musa acuminata, AAA Group, locally called cv. Hom Thong) by immersing fruits in hot water (50 °C) for 10 min, before storage at 25 °C for 10 days or 14 °C for the first 8 days followed by storage at 25 °C for the second 8 days until ripening. Quality parameters including peel color and pulp firmness indicated that hot water treatment helped to delay banana fruit ripening at both storage conditions. Hot water treatment decreased the levels of hydrogen peroxide (H₂O₂) and malonydialdehyde (MDA) during storage at 25 °C. Glutathione (GSH and GSSG) contents and the ratio of GSH/GSSG during fruit approaching ripening were significantly induced in hot water-treated fruits while ascorbic acid (AA) contents were slightly increased. In addition, the combined treatment increased free phenolics and flavonoids during storage. Results suggest that hot water treatment has led to an induction of antioxidants in banana fruits as indicated by an increase of antioxidants and a decrease of H₂O₂ during ripening, and all of which result in a delayed ripening of banana fruit.     

The post-harvest ripening of water stressed banana fruits

SUMMARY

Maintaining banana fruit in a low humidity environment accelerated fruit ripening. This was reflected in an earlier increase in respiration and ethylene production and more advanced peel colour and pulp sugars. At the end of the trial the fruit kept in low humidity were yellow with green tips (stage 5) whereas those kept at high humidity were still green (stage 1-2). Fruit kept at low humidity did not show a large increase in pulp ethylene production compared with the fruits stored at high humidity. This difference occurred despite a large increase in the 1-aminocyclopropane-l-carboxylic acid (ACC) content of both samples, with the low humidity fruit preceding the high by two days. The peel ethylene production of the low humidity stored fruit increased dramatically as the fruit ripened, coinciding with an increase in ACC. The ACC oxidase activity of the peel reflected the ethylene production with a large increase in the low humidity stored fruit and a later, smaller increase in the high humidity stored fruit. The ACC oxidase activity of the pulp of both low and high humidity stored fruit increased gradually during storage. The changes in ethylene production are discussed with reference to banana ripening being regarded as co-ordinated by pulp ethylene production while the peel is passive, depending on pulp ethylene production for degreening.     

Involvement of 1-methylcyclopropene in ripening of harvested mei (Prunus mume) fruit

Summary

Harvested mei (Prunus mume) fruit were stored at 20°C after exposure to 500 nl l^–1 1-methylcyclopropene (1-MCP) for 8 h. Firmness, peel colour, chlorophyll content, chlorophyllase activity, soluble solids content (SSC), titratable acidity (TA), respiration and ethylene production, and cell wall hydrolysis enzyme activities were monitored to determine the efficacy of 1-MCP treatment in delaying mei fruit ripening compared to untreated control fruit. Results showed that control ‘daqinghe’ mei fruit displayed typical climacteric patterns of respiration and ethylene production. Peak CO₂ production and ethylene production were observed after 6 d. Fruit softening was accompanied by a progressive decrease in colour parameters expressed as hue angle (h°), chlorophyll content, SSC, TA and increases in chlorophyllase, pectin methylesterase (PME) and polygalacturonase (PG) activities. 1-MCP treatment prior to the climacteric increase significantly delayed the onset of the climacteric peaks of CO₂ and ethylene production. These delays were associated with reductions in fruit softening, consistent with delaying the activities of PME and PG. Fruit treated with 1-MCP exhibited less peel colour change from green-to-yellow because of their lower levels of chlorophyllase activity and less chlorophyll breakdown. Moreover, 1-MCP treatment also significantly retarded reductions in SSC and TA compared with control fruit. The shelf-life of mei fruit ripening was increased by 4 d following 1-MCP treatment. Thus, 1-MCP treatment can markedly extend the post-harvest life of ‘daqinghe’ mei fruit.     

1-甲基环丙烯对高温下香蕉果实后熟的影响

以香蕉果实为试材,研究了1-甲基环丙烯(1-MCP)对高温逆境下香蕉果实后熟生理的影响。结果表明:35℃高温下贮藏的香蕉果实出现了明显的青皮熟现象,而0.5μL/L的1-MCP处理24h后可显著抑制高温下贮藏果实硬度的降低,延缓果皮细胞膜透性的升高,同时有效地延迟了果肉中淀粉酶活性升高、淀粉含量下降及可溶性糖含量上升。1-MCP处理果实于35℃下贮藏9d后移入20℃环境,进一步延缓了这些后熟生理变化。1-MCP和高温均抑制了果皮叶绿素含量下降,因此1-MCP处理减轻了香蕉热害的程度,延长了果实在高温下的贮藏寿命。     

青梅果实的采后成熟特性和肉质变化

研究了２０℃,相对湿度９３％条件下青梅果实的采后成熟特性和肉质变化,结果表明,青梅果实采后呼吸活性和乙烯生成量随着成熟作用的进展而加大,乙烯生成量极高,在呼吸类型上属于跃变型果实;果皮急速黄化,果肉急速软化,主要原因在于多聚半乳糖醛酸酶,果胶甲酯酶活性的增大,导致水溶性果胶含量上升和盐酸可溶性果胶含量的下降。     

香蕉泛素结合酶基因与果实成熟关系的研究

根据香蕉果实采后早期成熟的抑制缩减杂交文库获得的香蕉泛素结合酶基因片段,从香蕉（Musa acuminate L. AAA group‘Brazilian’）果实中克隆了泛素结合酶基因的cDNA全长,命名为MaUCE1。该cDNA全长890 bp,编码152个氨基酸。BlastX分析表明,该基因所推导的氨基酸序列与烟草（BAB40310）、小麦（AAA34310）、拟南芥（L19351）和马铃薯（ABA46759）有较高的一致性（95.39%、95.39%、92.11%和90.79%）,并且结构域分析发现该序列具有泛素结合酶E2的酶活性中心部位和一个与其他真核生物泛素E2酶相同,在泛素E2硫酯键形成中具有催化活性,并在进化上高度保守的半胱氨酸残基。该基因在香蕉根、茎、叶、花、果实中均有表达,但在花和果实中的表达量较高,并且在果实成熟后期表达量升高,与淀粉磷酸化酶活性变化一致,与淀粉含量的变化呈负相关,暗示该基因可能参与香蕉果实成熟过程中的分解代谢,而与果实成熟启动无关。     

Effects of short-term N2 treatments on ripening of banana fruit

Summary

Experiments were conducted to evaluate the effects of anoxia treatments on banana fruit ripening. Pre-climacteric banana fruit were exposed to pure N₂ for 0, 6, 9, 12 or 24 h, then stored for up to 3 weeks at 20°C and approx. 90% relative humidity. Changes in peel colour, fruit firmness and post-harvest life were evaluated. Ripening was inhibited most effectively in fruit exposed to N₂ for 9 h. Furthermore, exposure of banana fruit to pure N₂ gas for 9 h reduced the rates of ethylene production and respiration, as well as the activities of polygalacturonase and pectin methyl esterase. These results suggest that anoxia treatment is a feasible technology to inhibit ripening and extend the shelf-life of banana fruit.     

低温对香蕉叶片中甘油等物质含量的影响

在人工降温过程中,大蕉和香蕉叶片中甘油、可溶性总糖和还原糖的含量均随着温度的降低而上升,且在整个降温过程中,抗冷性较强的大蕉叶片中甘油、可溶性总糖和还原糖的含量一直高于抗冷性相对较弱的香蕉。低温胁迫下淀粉与糖之间的转化,大蕉和香蕉分别发生在不同的温度点。低温胁迫下,植物叶片中甘油等物质的含量及淀粉与糖之间的转化与植物的抗冷性密切相关。