Analysis of sake making procedures accelerating dimethyl trisulfide formation during sake storage

Abstract

Dimethyl trisulfide（DMTS） is responsible for hineka, an off-flavor in sake that develops during storage. We analyzed sake samples which were donated by sake companies, and extracted and demonstrated 4 sake making factors which could possibly affect DMTS concentration in sake after 7 days of storage at 70 ℃（DMTS-pp）：differences in yeast strains, differences in shubo（yeast seed mash called kimoto or sokujomoto） making methods with or without of the addition of alcohol to moromi, and differences in moromi pressing methods. Small scale fermentation tests and comparisons of sake commercially made with similar conditions except for shubo revealed that the differences in yeast strains and the differences in shubo making scarcely affect DMTS-pp. On the other hand, we found that the addition of alcohol to moromi decreased DMTS-pp, probably due to a dilution effect, and that DMTS-pp decreased more than the dilution ratio. Also, the pressing process of sake mash was found to affect DMTS-pp. Seme（later fraction of sake obtained under high pressure） has a higher DMTS-pp compared with arabashiri（free run fraction） and nakadare（middle fraction）. In seme, absorbance at 260 nm was higher than that of arabashiri and nakadare. These results suggest that yeast cell leakage may affect DMTS-pp in seme.