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Reconsideration of the mechanism of astringency loss on persimnon fruit.

柿果涩味损失机制的再思考

基本信息

批准号：
06454055
负责人：
YONEMORI Keizo
金额：
$ 4.03万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06454055/
关键词：
tannins tannin cell Diospyros kaki astringency molecular weight micromanipulator

项目摘要

In order to reconsider the mechanism of astringency removal and to study the nature of tannin cells, we carried out the following studies :1.Astringency of the fruit was removed by ethanol vapor on the tree or in a desiccator after harvesting. Coagulated tannins from the fruit whose astringency was removed on the tree could be resolubilized in HCl-MeOH unless browning reaction of the flesh was completed. However, coagulated tannins could not be resolubilized in the fruit whose astringency was removed in a desiccator, despite of the absence of browning reaction. These results indicate that coagulated tannins have several states in reactions.2.Gel chromatography of tannins resolubilized with HCl-MeOH from ethanol-treated fruit showed smaller molecular size when compared with tannins extracted with MeOH from untreated astringent fruit. Tannins extracted with HCl-MeOH from untreated astringent fruit also showed smaller molecular size than tannins extracted with MeOH from the same fruit. This result shows an involvement of noncovalent bonds in coagulation.3.We developed a method for collecting and analyzing cell saps from intact cells. Thin section of fruit flesh of mature fruit was put on a glass side, and a micropipette was inserted into a cell to withdraw its contents. By this method, we could collect about 5 or 7nl of cell sap per tannin cell, while about 2nl per parenchymatous.4.When tannin content and sugar constituents in collected cell saps were determined, tannin cells contained 10 to 12% of tannins and 10 to 13% of soluble sugars, while parenchymatous cells contained trace amounts of tannins and about 20% of soluble sugars. It was interesting that tannin cells contained only slight amount of sucrose, in contrast with relatively high ratio of sucrose in parenchymatous cells.

为了重新思考涩味去除的机制，研究单宁细胞的性质，我们进行了以下研究：果实的涩味是用乙醇蒸汽在树上或在收获后的干燥器中去除的。在树上去除涩味的果实中凝固的单宁可以在盐酸-甲醇中溶解，除非果肉的褐变反应完成。然而，在干燥器中去除涩味的水果中，尽管没有褐变反应，但凝固的单宁不能被分解。这些结果表明，混凝单宁在反应中具有多种状态。凝胶层析结果表明，与甲醇提取的单宁相比，甲醇提取的单宁分子量更小。从未处理的涩味果实中，用盐酸-甲醇提取的单宁的分子大小也比用甲醇提取的单宁小。这一结果表明非共价键参与了凝固过程。我们开发了一种从完整细胞中收集和分析细胞液的方法。将成熟水果的果肉薄片置于玻璃面，将微移液管插入细胞中提取其内容物。通过这种方法，每个单宁细胞可收集到5 ~ 7nl的细胞液，每个薄壁细胞可收集到2nl的细胞液。当测定所收集的细胞液中的单宁含量和糖成分时，单宁细胞含有10 - 12%的单宁和10 - 13%的可溶性糖，而薄壁细胞含有微量的单宁和约20%的可溶性糖。有趣的是，单宁细胞中蔗糖的含量很少，而薄壁细胞中蔗糖的含量相对较高。