Aromatic compounds, such as cinnamic, p coumaric (4 hydroxycinnamic), and ferulic (4 hydroxy 3 methoxycinnamic) acids, have antimicrobial activity toward microorganisms, including yeast and fungi. To evaluate the mechanism for ferulic acid tolerance in Saccharomyces cerevisiae, mutants which could grow in medium containing 0.08%(w/v) ferulic acid were isolated and characterized. The Saccharomyces ccwrisiac strain X 2180 1 11 (MATα) was treated with ethylmethane sulfonate and selected on 0.5% malt extract, 0.01% yeast extract agar medium (MYE) containing 0.8 g per ferulic acid. By primary screening in M YE liquid medium containing 0.08% 4; ferulic acid and by secondary screening on the same agar medium, two mutant strains, designated α 1 and α 2, were isolated and further characterized. The two mutants were insensitive to the cell wall lysis enzyme Zymolyase 20 T and to cycloheximide, but were sensitive to cerulenin. The two mutants also converted ferulic acid into 4 vinylguaiacol, and the decarboxylase activity of the mutants was greater than that of the wild type, the wine yeast strain W 1, and the sake yeast strain Kyokai No.7. These results suggest that the decarboxylation of ferulic acid by biotransformation is related to the ferulic acid tolerance.
The effect of conditions in the steamed rice cooling process on aging was investigated. The level of humidity in the cooling process had a great effect onthe aging of the steamed rice. In Ginjo sake brewing that used aged rice as the Kakemai, a Ginjo sake with a lower alcohol yield, acidity, amino acidity, OD 260, OD 280, and ethyl caproate concentration and a higher ratio of sake cake, and isoamyl alcohol than the control was obtained.
The effects of temperature and time on koji making were investigated using the rice koji that is used to brew ginjo-shu in Shimane Prefecture. Aseries 41 time periods was investigated using three kinds of koji (Soe-koji, Naka-koji and Tome-koji). A change in temperature made no diffence to enzyme activity, but changing the time periodproduced diffence when compared to the control.The integration of temperature and glucoamylaseactivity during the proccessing of Shimaishigoto (The 2 nd mixing stage in koji-making) and De-koji (The last prosess) showed a good correlation.(0.88 correlation coefficient) Therefore, it was proved that glucoamylase activity tends to increase according to the integration temperature of ginjo-koji.