SummaryThe characteristics of removal of astringency of two Japanese persimmon (Diospyros kaki Thunb.) cultivars, `Denkuro' and `Hiratanenashi', when treated with warm water, ethanol vapor and CO2 gas, were investigated.The patterns of the changes in peel color and flesh firmness were much the same for each treatment in both cultivars.The astringency of `Denkuro' and `Hiratanenashi' fruits was removed with both warm water and CO2 treatments. Decrease of soluble tannin occurred earlier in `Denkuro' than in `Hiratanenashi' in warm water treatment. In the ethanol treatment, astringency of `Hiratanenashi' was removed gradually and thoroughly, whereas there was almost no decrease of soluble tannin in `Denkuro' for 6 days.Ethanol and acetaldehyde accumulated in the flesh earlier and their levels were a little higher in `Denkuro' than in `Hiratanenashi' fruits when treated with warm water. The patterns of ethanol and acetaldehyde accumulation were almost the same in CO2 treatment in the two cultivars. In ethanol treatment, much more ethanol accumulated in `Denkuro' than in `Hiratanenashi' fruits, but only little acetaldehyde was detected in `Denkuro' , while a small but obvious amount accumulated in `Hiratanenashi'. The decrease of soluble tannin was, on the whole, closely related to the level of acetaldehyde accumulation in both cultivars.The responses of fresh juice to acetaldehyde vapor seemed almost the same between the two cultivars.From these results, the cultivar differences between `Denkuro' and `Hiratanenashi' and their regulative mechanisms in removing astringency were discussed.

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