n the present study, we examined the effects of yeast cell death in sake mash and the cell-free extract prepared from these yeast cells on DMTS formation, based on the hypothesis that yeast cell lysis in sake mash promotes DMTS formation.
Small-scale brewing of sake using 400 g of total rice was performed according to the methods of Namba et al. (12). Fermentation was performed at a maximum temperature of 13°C for 6, 8, or 11 days or at 15°C for 4, 6, or 9 days to obtain sake samples with different yeast methylene blue (MB) staining ratios in sake mash at the end of fermentation. Furthermore, the fermentation temperature was decreased by 1°C per day until the total fermentation period reached 17 days. The MB staining ratios and properties of the produced sake samples are summarized in Table 1. We determined the DMTS-producing potential (DMTS-pp) of each sake sample and the correlation coefficients between DMTS-pp and other analyzed values (Table 1). DMTS-pp indicates the strength of hineka after storage, and is estimated by the DMTS concentration in sake after accelerated aging at 70°C for 7 days (4).