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梨果肉酶促褐变机理研究

标题: 梨果肉酶促褐变机理研究
英文标题: The Mechanism Research of Enzymatic Browning in Pear Flesh
作者: 邹丽红
出版时间: 2012-01-01
所在大学: 河北农业大学
关键词: 梨,酶促褐变,酚类物质,褐变相关酶
英文关键词: pear,enzymatic browning,phenolic compounds,enzymes in relation to enzymatic browning
论文级别: 硕士
学位: 学位论文
导师: 张玉星
专业: 园艺产品质量与安全
提交时间: 2012
摘要: 为了探明梨果肉酶促褐变的内在机制,以4大梨系统和梨新品种共49个品种的果肉为试材,测定了果肉酚类物质组分及含量、褐变相关酶活性(PPO、POD、PAL、SOD、CAT、LOX)及GSH、可溶性蛋白、MDA含量等相关生理生化指标,得到了以下主要结果:1.不同品种梨果肉的褐变程度各异,面梨和八里香褐变程度最重,雪青和丰水褐变度最低;秋子梨系统果肉的总酚和总黄酮含量显著高于其它梨系统.白梨、砂梨、西洋梨、新品种梨果肉总酚含量与褐变度趋势大致相同.2.不同品种梨果肉酚类物质组成和含量不同,各品种大都可检测出熊果苷、没食子酸、绿原酸、儿茶素、表儿茶素、咖啡酸、香草酸、芦丁、对香豆酸、香草醛、阿魏酸、槲皮素和肉桂酸,但新高梨果肉中未检测到儿茶素,幸水梨未检出阿魏酸,茌梨、大慈和砀山酥梨未检出表儿茶素;供试49个品种中含量最多的酚类物质组分是熊果苷和绿原酸;秋子梨果肉熊果苷、绿原酸、儿茶素和表儿茶素含量均显著高于其他梨系统;绿原酸含量总体趋势为:秋子梨>白梨>西洋梨>砂梨,熊果苷含量以西洋梨果肉中最少.3.各因子对酶促褐变的作用高低顺序为总黄酮>表儿茶素>总酚>POD>对香豆酸>儿茶素>绿原酸>可溶性蛋白>熊果苷>咖啡酸> GSH>CAT>PAL>芥子酸.其中总酚、总黄酮、绿原酸、表儿茶素、儿茶素、咖啡酸、POD、PAL、芥子酸、熊果苷与果肉褐变呈极显著正相关,CAT、GSH、可溶性蛋白与褐变呈显著负相关,但其对褐变的作用却最弱.总黄酮是影响梨果实褐变最重要的因素,表儿茶素次之,PAL和芥子酸最低.不同酚类物质组分中表儿茶素是影响梨果肉褐变最主要的因素.故总黄酮、表儿茶素、总酚含量是影响梨果肉酶促褐变的关键因子.4.梨果肉褐变相关酶活性和非酶类物质含量因品种不同而存在差异,且其对酶促褐变的影响亦因品种而异;PPO活性与梨果肉酶促褐变无显著相关性.5. POD与梨果肉酶促褐变的相关性显著高于其它酶类和非酶类物质.
英文摘要: With 49 pear cultivars which belonging to four species and hybrid varieties as the experimental materials, total phenol and phenolic composition contents, GSH, MDA, and Soluble protein content, PPO, SOD, CAT, PAL, and POD activities in fruits were studied. The aim is to reveal the internal mechanism of enzymatic browning. The main results are as follows:1. The enzymatic browning level exhibited larger difference among individual cultivars, and the browning of Mianli pear and Balixiang was severer while Manfeng and Hosui was less. Total phenol and Total flavonoids contents in Pyrus ussriensis Maxim fruits were Significantly higher than other species. Among the different varieties, Total phenols content and browning degrees roughly had the same trend.2. 14 different phenolic compounds were determined in fresh fruit by high performance liquid chromatography analysis. The content of phenolic compounds showed high difference among different cultivars and species. Average content of chlorogenic acid and arbutin were the highest, and followed by catechin, epicatechin, violaquereitrin and rutin in sequence. Therefore, these six phenolic compounds were major phenolic substances in pear fruit; however, average content of vanillin and cinnamic acid were the lowest. Content of arbutin, chlorogenic acid, catechin, epicatechin in fruits of Pyrus ussriensis Maxim were higher than hybrid cultivars and other species. From high to low order, the overall trends of chlorogenic acid content were Pyrus ussriensis Maxim, Pyrus bretschneideri Rehd. , Pyrus communis L. , Pyrus pyrifolia Nakai in sequence. Content of arbutin in Pyrus communis L.was the lowest.3. The role of each factor on browning in a descending order were total flavonoids >epicatechin> total phenols> POD> coumaric acid> catechin> chlorogenic acid >soluble protein> arbutin> caffeic acid> GSH> CAT>PAL> sinapic acid. Among them , total phenol, total flavonoids, chlorogenic acid, epicatechin, catechin, caffeic acid and POD, PAL, Sinapic acid, arbutin were highly significantly positive correlations with browning. CAT, GSH and soluble solids which had slight effect on enzymatic browning were significant negative correlations with browning. total flavonoids was the main factor which influenced enzymatic Browning in pear flesh, followed by epicatechin, PAL and sinapic acid were lest. Of the different polyphenols components , catechins was the most important factor of browning in pear. So the content of total flavonoids, epicatechin, and total phenols were the main factors which influenced enzymatic Browning in pear flesh.4. Enzyme activitivies and contents of non-enzyme in relation to enzymatic browning varied with different varieties, which were also similarly its relationship with enzymatic browning.Activity of PPO and enzymatic browning were no significant correlation.5. The correlation of PPO to enzymatic browning in fruits was higher than that with enzymes and non-enzymes.