Changes in the Composition of Japanese Persimmon "Sanja" Juice during Alcohol Fermentation

Studies on Utilization of Astringent Japanese Persimmon cv. Sanja part II

Abstract

The alcohol fermentation of de-astringent Japanese persimmon (cv. Sanja) juice was carried out for the purpose of vineger production and changes in contents of organic acids, sugars and free amino acids during the fermentation were investigated. Most of the ethanol was produced in 3 days after inoculation of the 5% of precultured wine yeast and the ethanol concentration was finally reached to 6.2% (w/v) in 6 days. Though malic and galacturonic acids were abundant in the juice, malic acid decreased rapidly comparing with galacturonic acid during the fermentation. Glucose (5.54%) and fructose (5.03%) were the dominant sugars in the juice before the fermentation. They decreased abruptly during 2-3 days after inoculation, and glucose waS consumed more rapidly than fructose. The main free amino acids in the juice were glutamine and γ-amino-n-butyric acid. While most of free amino acids decreased during the fermentation, proline increased up to 67% of total free amino acids 6 days after the fermentation. The yellowish light orange and slightly cloudy product had light and slightly sour taste. The astringency was not perceived.