【作者】 孟祥勇；

【导师】 张慜；

【作者基本信息】 江南大学 ， 食品科学， 2013， 博士

【摘要】 新鲜果蔬经鲜切加工后,其组织结构受到不同程度的破坏,诱导了一系列的生理生化反应,且容易受到微生物的侵染,造成鲜切果蔬品质劣变,缩短了货架期。针对上述问题,本文以鲜切青椒和黄瓜为研究对象,系统研究了加压惰性气体及其联合处理对鲜切蔬菜生理、品质和微生物影响的作用规律,建立贮藏条件和品质特性之间的数学模型。为了探明加压氩气处理对鲜切蔬菜保鲜效果的影响,首先考察了加压氩气处理对鲜切青椒呼吸代谢、褐变、营养特性及理化指标的影响。研究结果表明,加压氩气处理能够抑制鲜切青椒贮藏期间呼吸代谢,抑制了贮藏期间鲜切青椒中过氧化物酶(peroxidase, POD).苯丙氨酸氨解酶(phenylalanine ammonialyase, PAL)(?)口抗坏血酸氧化酶(ascorbic acid oxydose, AAO)酶活性的变化,减少了鲜切青椒中总酚、VC和β-胡萝卜素含量的损失；此外,研究还表明加压氩气处理还保持了鲜切青椒较高的抗氧化能力。为了进一步探明加压氩气处理对鲜切蔬菜保鲜的作用规律及机制,以鲜切黄瓜为研究对象,考察了加压氩气处理对鲜切黄瓜的水分流动性、失水率和生理代谢及品质的影响。研究结果表明,加压氩气处理抑制了鲜切黄瓜水分流动性,减少了鲜切黄瓜失水率,抑制了呼吸强度和乙烯生成量。同时,加压氩气处理维持了鲜切黄瓜细胞膜完整性,延缓了鲜切黄瓜的衰老。为了探明加压混合气体处理对鲜切蔬菜保鲜效果的影响,研究了加压混合惰性气体对鲜切青椒冷藏期间品质及生理特性的影响,结果表明加压混合气体(Ar+Kr)处理能够抑制冷藏期间鲜切青椒的呼吸强度,乙烯生成量,减少水分和硬度损失；同时,加压混合气体处理能够维持鲜切青椒细胞膜的完整性,减少了鲜切青椒冷藏期间丙二醛的生成；此外,研究结果还表明加压混合气体处理减少了VC含量的下降,延缓了贮藏期间鲜切青椒褐变的出现。通过比较发现,加压混合气惰性体处理对鲜切蔬菜(青椒)的保鲜效果低于加压氩气处理的保鲜效果,但优于加压氪气的效果。针对鲜切黄瓜贮藏期问品质易劣变和微生物易繁殖的特点,采用加压氩气结合纳米锌涂膜处理对鲜切黄瓜贮藏期间生理代谢和品质特性的影响进行研究。研究结果表明,加压氩气处理、纳米锌涂膜处理尤其是联合处理能够明显抑制贮藏期间鲜切黄瓜的呼吸代谢能力,降低了贮藏期间鲜切黄瓜的过氧化物酶(POD)和多酚氧化酶(PPO)的活性,延缓了贮藏期间鲜切黄瓜的Hue和L的变化,延缓了鲜切黄瓜的品质变化。此外,加压氩气、纳米锌涂膜以及加压氩气+纳米锌涂膜对鲜切黄瓜微生物生长具有明显的抑制作用,减少了贮藏期问鲜切黄瓜腐败变质并提高了食用安全性。为了对加压惰性气体处理鲜切青椒贮藏期间的品质进行预测,建立了多元线性回归模型和基于反向传播算法的非线性神经网络模型。研究结果表明,三层(4-5-4)BP神经网络模型具有良好的预测能力且优于多元线性回归模型,BP神经网络对b值、失水率、VC含量和硬度的预测接近于实测值。更多还原

【Abstract】 The tissue structure of fresh fruits and vegetables can be destroyed by the fresh-cut process which triggers the plant physiological reaction, leading to microbial growth and the deterioration of fresh-cut fruits and vegetables. It leads to the reduced shelf-life of fresh-cut fruits and vegetables. For extending the shelf life of fresh-cut fruits and vegetables, some treatments are neccessary. In this study, the effect of pressurized inert gases treatments, such as argon (Ar) and krypton (Kr), on physiological characteristics, quality parameters and microbial growth of fresh-cut green peppers&cucumbers was investigated. Moreover, the mathematical model was developed to evaluate the relation between the storage conditions and quality characteristics.In order to explore the effect of pressurized inert gases treatments on fresh-cut vegetables, the changes in respiration rate, ethylene production, browning, nutritional properties and physicochemical indexes were investigated. The results showed that pressurized argon treatments could inhibit respiratory metabolism, and the activities of peroxidase (POD), phenylalanine ammonialyase (PAL) and ascorbic acid oxydose (AAO) of fresh-cut green peppers treated with pressurized argon were lower than that of control samples. In addition, pressurized argon treatmentscould reduce the loss of VC, total phenols and beta-carotene. Furthermore, the antioxidant activities of fresh-cut green peppers treated with pressurized argon werehigher than that of control samples.In order to further explore the role and mechanism of pressurized argon treatments on preservation of fresh-cut vegetables, pressurized argon was used to treat fresh-cut cucumbers. The changes in water mobility, water loss, physiological metabolism and quality characteristics were investigated. The results showed that pressurized argon treatments were effective in reducing water mobility the loss of water. In addition, the respiratory metabolism of fresh-cut cucumbers was inhibited by pressurized argon treatments. Moreover, pressurized argon treatments maintained cell membrane integrity and delayed the senescence of fresh-cut cucumbers.In order to explore the effect of inert gas mixture treatments on fresh-cut vegetables, the effect of pressurized inert gas mixture (argon+krypton) on quality and physiological characteristics of fresh-cut green peppers during cold storage was investigated. The results showed that pressurized inert gas mixture of argon and krypton was effective in inhibiting respiration rate, ethylene production and the loss of water and firmness. In addition, it was found that the treatments of pressurized inert gas mixture could maintain the integrity of the cell membrane of fresh-cut green peppers, and reduce the production of malondialdehyde (MDA). Moreover, the treatments of pressurized inert gas mixture could reduce the loss of VC content and delay the incidence of browning of fresh-cut green peppers. By comparison, it was found that the effects of pressurized inert gas mixture treatments on fresh-cut green peppers were inferior to that of pressurized argon treatments, but superior to that pressurized krypton treatments.Based on quality deterioration and microbial growth characteristics of fresh-cut cucumbers, the effects of pressurized argon, nano-zinc oxide (ZnO) coating and their combination in maintaining the quality of fresh-cut cucumbers during storage were investigated. The results showed that pressurized argon treatments, nano-ZnO coating, especially mixed treatments were effective in inhibiting respiration rate and ethylene production of fresh-cut cucumbers. In addition, pressurized argon treatments, nano-ZnO coating and mixed treatments could inhibit the activity of peroxidase (POD) and polyphenol oxidase (PPO) of fresh-cut cucumbers. Furthermore, the combined treatments of pressurized argon and nano-ZnO coating were found to be more effective in reducing the population of Escherichia coli., Salmonella, molds and yeasts than other two treatments (pressurized argon, nano-ZnO coating), resulting in lower deterioration and higher edible security of fresh-cut cucumbers.In order to predict the quality of fresh-cut green peppers treated with pressurized argon, a multiple linear regression model and a nonlinear neural network model based on back propagation arithmetic were developed. The results showed that the three layers (4-5-4) BP neural network model has good predictive ability which was superior to that of multiple linear regression model. Based on the developed neural network model, the prediction of b value, VC content, water loss and firmness of fresh-cut green peppers was close to the measure values.更多还原