【作者】 许宙；

【导师】 周文化；

【作者基本信息】 中南林业科技大学 ， 农产品加工及贮藏工程， 2008， 硕士

【摘要】 鲜切果蔬是一种很具前景的即食性加工产品,因其具有新鲜、卫生、营养、方便等特性而深受消费者欢迎。然而切分表面发生褐变严重影响了其产品品质。本研究以砂梨(Pyrus pyrifolia)品系中最具代表的中国砂梨(黄花、金秋)和日本砂梨(新世纪、新高)为试材,分析不同品种砂梨在鲜切处理后生理状态的差异,不同加工方法对色泽的影响,并在此基础上,筛选出最佳配方复合护色剂,进行效果评价,以期为鲜切砂梨生产中克服或减缓褐变提供理论依据和实践指导。主要研究结果如下：1.以新世纪、新高、黄花和金秋四个品种砂梨为试材,分析不同品种砂梨在鲜切处理后生理状态的差异。结果表明：砂梨的褐变是由多种因素共同作用的结果,PPO、POD是影响褐变的关键酶,PPO与褐变的相关性大于POD。四个品种鲜切处理后褐变程度强弱依次是：新世纪>新高>金秋>黄花。2.以新世纪砂梨为试材,对切割方式、贮藏温度、壳聚糖浓度、护色液成分等影响鲜切砂梨褐变的因素进行了研究。结果表明：横切对褐变的影响小于纵切；低温贮藏(0℃和10℃)比室温(25℃)更有助于较长时间保持鲜切砂梨良好的色泽；在0.5%、1.0%、1.5%和2%壳聚糖浓度间,1.5%壳聚糖被膜对褐变的抑制效应更为显著；不同护色剂的护色效果的次序是：0.3%柠檬酸>0.5%抗坏血酸>0.1%甘露醇。3.以新世纪砂梨为试材筛选最佳护色剂组合,结果表明：复合护色剂中影响因子的作用依次为：B>C>A>A×B> B×C>A×C(A、B、C分别代表抗坏血酸、柠檬酸和甘露醇)；并通过多因素试验得到的最佳护色配方(0.3%抗坏血酸+0.5%柠檬酸+0.1%甘露醇)。4.以新世纪、新高、黄花和金秋四个品种砂梨为试材,进行最佳护色剂组合的效果评价。测定经最佳护色保鲜剂处理后四贮藏期间四个品种的BD值、呼吸强度、PPO活性、POD活性、SOD活性、PPO同工酶、POD同工酶和SOD同工酶等指标。结果显示：复合护色剂对四个品种鲜切砂梨抑制褐变度的效果依次是：新世纪>金秋>新高>黄花；复合护色剂处理对各品种的呼吸强度影响不大；复合护色剂能使全部测试砂梨品种鲜切处理贮藏前期(0-6 d)PPO、POD活性有效降低,SOD活性有效增高；PPO, POD, SOD同工酶的对照与护色处理间存在一定差异,主要表现在区带数目,但是这种差异不太明显。更多还原

【Abstract】 Fresh-cut fruit and vegetable, characterized by fresh, nutritional and ready-to-eat, is a rising and popular product. But the mechanical processing browns the cutting surface which resulted in quality deterioration. In this paper, Chinese sand pear (Huanghua, Jinqiu) and Japanese sand pear (Niitaka, Shinseiki), represent-tative strains of sand pear(Pyrus pyrifolia)were used as experimental materials, to analyse the physiological situation difference in varieties of fresh-cut sand pears and the effect of different processing method on the color of pears.Based on those obtained results, optimum compound inhibitors for controlling browning was screened out then made an effect evaluation to provide theoretical basis and practical guidance for reducing browning of fresh-cut fruit sand pears.The main results showed as followings:1. Niitaka pear, Huanghua pear, Jinqiu pear and Shinseiki pear were used as experimental materials, to analyse the physiological situation difference in varieties of fresh-cut sand pears. The result indicated that browning of sand pear were affected by different complex factors. PPO and POD were the key enzymes resulting in browning. BD (browning degree) of four varieties of fresh-cut sand pears ranked from high to low as following:Shinseiki ranked first,and the Niitaka were second, Jinqiu and Huanghua ranked third and fourth respectively.2. Shinseiki were used as experimental materials, to study on the affected factors such as cutting way, storage temperature, chitosan concentration,fresh fixative composition, ect of BD. The result indicated that the effects of cross cut on BD was superior to slitting; the effects of cryopreservation (0℃to 10℃)on keeping the color of fresh-cut sand pear were superior to room temperature (25℃); in the chitosan concentration of 0.5%,1.0%,1.5% and 2%, the inhibitory effect of 1.5% chitosan concentration on BD was significant higher than others; the effect of fresh fixative on pears ranked from high to low as following:0.3% citric acid>0.5% ascorbic acid>0.1% mannitol.3. In multiple factors test of compound fresh fixative on inhibition of bro-wning, the effect of different compound on controlling browning of Shinseiki pear ranked from high to low as following:citric acid> mannitol>ascorbic acid> ascorbic acid X citric acid> citric acid X mannitol> ascorbic acid X mannitol; and obtaining the best formula of inhibition (0.3% citric acid+0.5% ascor bic acid+ 0.1% mannitol).4. Niitaka pear, Huanghua pear, Jinqiu pear and Shinseiki pear were used as experimental materials, to evaluate the effect of the optimum formula of inhibi-tion. During storage period, the index of BD value, respiratory intensity, activity of PPO and POD, isozyme of PPO, POD and SOD of optimum formula of inhibition of four varieties of fresh-cut sand pears were measure. The result indicated that compound inhibitors had small effect on respiratory intensity of varieties of fresh-cut sand pears;the compound inhibitor could keep sand pear cutting of the 4 varieties fresh within 6 day-stortage. The compound inhibitors could reduce the activity of PPO and POD, and enhance the activity of SOD on all varieties of sand pear; isozyme of PPO, POD and SOD showed that differ-rences existed among control and treated materials mainly in the number of zone, but the difference was not significant.更多还原