1986 Volume 55 Issue 2 Pages 228-234
It has been thought that natural removal of astringency in three types of Japanese persimmon fruits, i.e. pollination-variant/astringent (PVA), pollination-variant/nonastringent (PVNA) and pollination-constant/astringent (PCA), depends on the level of volatile compounds such as ethanol and acetaldehyde produced by their seeds during fruit development. We studied the internal gas condition of the fruit in relation to ethanol production by the seeds, and also examined the effect of several artificial gas environments on detached whole fruits or excised seeds.
1) Ethanol production by the seeds of any type of fruit seemed to be partly triggered by the anaerobic conditions and high carbon dioxide concentration generated in the early stage of fruit development. No differences in the degree of anaerobicity were observed between the fruit types.
2) When whole fruits or excised seeds were placed in different concentrations of gas mixtures (N2, O2 and CO2), PVNA seeds produced more ethanol than PCA seeds under given anaerobic conditions.
3) In conclusion, the level of ethanol production by the seeds mainly reflected the differences in their inherent ethanol producing capacity. The observed differences may partly be due to differences in permeability of the seed coats to ethanol, resulting in a differential ability to remove astringency.