DIFFERENCES BETWEEN THE JAPANESE PERSIMMON (DIOSPYROS-KAKI THUNB) DENKURO AND HIRATANENASHI ON ACETALDEHYDE PRODUCTION BY THEIR FLESH DISKS

Comparison in acetaldehyde production by flesh discs was made to elucidate cultivar diffrences between 'Denkuro' and 'Hiratanenashi' persiommons with respect to the ease of removing their astringency. Soaking of flesh discs of immature astringent fruits in buffer containing ethanol caused more acetaldehyde production in 'Hiratanenashi' than in 'Denkuro'. When 4-methylpyrazole, an alcohol dehydrogenase inhibitor, was added to the same buffer, acetaldehyde production was partly inhibited in 'Hiratanenashi' discs, but not in those of 'Denkuro'. The addition of pyruvate or malate to the buffer increased acetaldehyde production in both cultivars, but at the same substrate level, discs of 'Denkuro' produced more acetaldehyde than did those of 'Hiratanenashi'; higher concentrations of pyruvate or malate tended to inhibit the reaction. The results indicate that 'Hiratanenashi' converts ethanol to acetaldehyde more efficiently than does 'Denkuro', whereas 'Denkuro' metabolizes pyruvate more readily to acetaldehyde than does 'Hiratanenashi'.