Relationships of Ethanol Production by Seeds of Different Types of Japanese Persimmons and Their Tannin Content

Abstract

Ethanol production in the seeds and its accumulation in the flesh were compared among 47 Japanese persimmon cultivars (Diospyros kaki L.) in relation to their degree of astringency. Those which produce relatively high amounts of ethanol and accumulate it in the flesh, i.e. pollination-variant/nonastringent (PVNA) cultivars, lose astringency on the tree, while those producing less ethanol, i.e. pollination-variant/astringent (PVA) ones, remain astringent. Pollination-constant/nonastringent (PCNA) and pollination-constant/astringent (PCA) cultivars generally produced little ethanol in the seeds and accumulated small amounts or none in the flesh. Thus, 2 different mechanisms exist that are involved in the loss of astringency. One is associated with PVNA, PVA, and PCA types and is dependent upon the production and accumulation of ethanol and presumably acetaldehyde. The second is associated with PCNA types which apparently do not produce these volatile substances.