Studies on the removal of the astringency and storage of Kaki (Oriental Persimmons) I

Microscopic observation of tannin cells in non-astringent fruits

Abstract

There are two types of fruits in non-astringent Kaki. One is the mature fruits of non-astringent cultivars which become edible naturally on the tree. The other type is the fruits of astringent cultivars which were treated with alcohol, carbon dioxide or warm water, or were over-ripened, stored frozen, or dryed after harvest. In the present report, tannin cells of these non-astringent fruits were examined microscopically and placed into five classifications according to the appearance of their protoplast and cell wall.
1) Brown: The protoplast is coagulated, shrunken and brown. Found in fruits of non-astringent and astringent cultivars which form brown specks in flesh when they mature (Fig. 1).
2) Shrunken: Whole tannin cell is shrunken and the protoplast is coagulated. Found in dryed fruits (Fig. 2).
3) Coagulated: The protoplast is coagulated. Found abundantly in fruits treated with carbon dioxide (Fig. 4-lower), alcohol or warm water (Fig. 3 -lower). Also found in dryed or frozen stored fruits and in fruits of non-astringent cultivars (Fig. 3-upper, 4-upper).
4) Plasmolyzed: The protoplast is not coagulated and is plasmolyzed easily. Found abundantly in over-ripened (Fig. 5) or gamma ray irradiated fruits and in fruits of non-astringent cultivars which do not form brown specks when they mature (Fig. 6). Also found occasionally in fruits treated with alcohol and in fruits of non-astringent cultivars which form brown specks. In this case, the astringent substance is not coagulated in tannin cells, but when plasmoptysis occurs it coagulates instantaneously (Fig. 7).
5) Ruptured: The cell is ruptured and the protoplast exudes. Found in frozen stored fruits (Fig. 8).