1995 Fiscal Year Final Research Report Summary
Reconsideration of the mechanism of astringency loss on persimnon fruit.
| Project/Area Number |
06454055
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
園芸・造園学
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
YONEMORI Keizo Kyoto Univ., Dept.of Agr., Asscoiate Prof., 農学部, 助教授 (10111949)
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| Co-Investigator(Kenkyū-buntansha) |
MOTOSUGI Hino Kyoto Univ., Dept.of Agr., Instructor, 農学部, 助手 (10182172)
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| Project Period (FY) |
1994 – 1995
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| Keywords | tannins / tannin cell / Diospyros kaki / astringency / molecular weight / micromanipulator |
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| Research Abstract |
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.
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