柿果のヴイタミンC及び酸化酵素に就て

Abstract

Varieties of Kaki (Diospyros Kaki) are used to be classified into two forms, pollination constant and pollination variant. In the former, the brown dots are never seen in the fruit flesh even in the seeded fruit, but in th latter, the browning of the flesh occurs in proportional intensity to the number of seed developed. The classification is applicable to the astringent as well as the non-astringent varieties. The brown dot is the tannin cell with coagulated and oxidized contents in it. The oxidation of the contents in the tannin cell may be brought about by the activity of oxidizing enzymes. The present study is carried out to accertain the relation of oxidizing enzymes to the browning of fruit flesh on the one hand, and to make oonsiderations of an analogous mechanism of oxidizing enzymes to the colour change of fruit into dull grey after artificial removal of astringency on the other.The writer tested the peroxidase and oxidase reactions with 24 varieties. The reaction of peroxidase is measured by WILLSTAETTER'S pyrogallol method, and of oxidase with guaiac tincture.SZENT GYORGYI's hypothesis, which denotes that the peroxidase is in close relation to ascorbic acid in a respiratory system, is taken into account and ascorbic acid (reduced form) is measured by the titration method after TILLMAN's 2.6-dichlorphenol-indophenol with 41 varieties.Further, the influence of artificial processing to remove the astringency and of the short day treatment on the oxidizing enzymes and ascorbic acid content is studied.The experimental results are summarized as follows:1. Ascorbic acid content is higher in the pollination constant than in pollination variant. The contrast is especialy remarkable in the non-astringent varieties. These results indicate that the ascorbic acid is found in the inverse proportion to the occurrence of brown dot.2. The activity of peroxidase correlates to the density of brown dots, and the most intensitive reaction of peroxidase is represented in the non-astringent pollination variant.3. The reaction of oxidase is concurrent with that of peroxidase in any case.4. After the artificial removal of astringency of astringent fruit, ascorbic acid decreases, though the activities of oxidizing enzymes being not influenced.5. By the short day treatment, ascorbic acid decreases, and the reaction of oxidizing enzymes increases.