Study On Natural Loss Property Of Astringency In 'Eshi 1', A PCNA Cultivar Newly Found In Central China

Japanese persimmon (Diospyros kaki Thunb.) cultivars are classified into four types depending on the nature of astringency loss of the fruit: PCNA(Pollination-constant non-astringent), PVNA(Pollination-variant nonastringent), PVA(Pollination-variant astringent) and PCA(Pollination-constant astringent). According to the Japanese scholar's viewpoits, the astringency loss property of ' Luotian-tianshi' persimmon which is a native Chinese PCNA type, is different from Japanese PCNA types, probably because of soluble tannins change into insoluble. 'Eshi 1' is a Chinese PCNA type, which was newly found in Dabieshan region except 'Luotian-tianshi' persimmon. It has bigger fruit and fewer seeds than 'Luotian-tianshi', and more valuable to breeding and planting. But it's nature of astringency loss has few reports.In this study, 'Eshi 1'(PCNA, China origin), 'Okitsu-20' (PCNA, Japan origin)and 'Mopanshi' (PCA, China origin) were used as materials to examine the changes of the tannin content and the tannin cells size after astringency-loss by ethanol treatment. The main results are as follows:1. The soluble and insoluble tannin has no remarkable difference about control and package about the three persimmon cultivars; By the observation of the tannin cells and determination of the tannin content in fruits in the early July and the middle of September, the content of soluble tannin has a remakble reduction and the content of insoluble tannin has a great increase, but the tannin cells has no remarkble difference about 'Eshi 1', so the conclution indicate that: 'Eshi 1' has tannin cell's dilution . 'Mopanshi' also has the soluble tannins reduction and insoluble tannins increase, but the tannin cells has a great increase. About 'Okitsu-20' ,there are no difference about the soluble and insoluble tannin content and the tannin cells size.By the observation of the tannin cells and determination of the tannin content in fruits after ethanol treament, we found that: the content of soluble tannin was under 0.2% and the content of insoluble tannin has a great increase about 'Eshi 1' and 'Mopanshi'. But ethanol treatment had no effect of the content of tannin about 'Okitsu-20'. After treatment, the size of tannin cells change small. So the conclusions indicate that: the nature of astringency loss of Chinese native cultivar 'Eshi 1' are dilution of tannin concentration and coagulation of soluble tannin.2. After optimizing the chromatographic conditions of the phenolic standards, the chromatographic separation was carried out using mobile phase methanol as solvent A and 1.5% Acetic acid as solvent B on C₁₈ column. A reversed-phase high-performance liquid chromatography (RP-HPLC) separation method with ultraviolet detector was developed to determine the catechin((+)-C), gallic acid(GA).