清酒もろみにおける脂質の変化〔清酒醸造における脂質の動向-4-〕

概要

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The changes of lipids during sake mash fermentation were investigated. As the fermentation proceeded, raw materials such as steamed rice and rice-koji were digested and solid fraction in mash decreased, and about 58% of fat-by-hydrolysis of raw materials became extractable with ether. Because of the low solubility of lipid in water, a large proportion of lipids remained in the decreasing solid fraction. A small amount of lipid was liberated in liquor fraction (liberated lipid:I), which increased according to the increase of alcohol concentration in mash and reached about 500 ppm of the liquor fraction at the final stage of fermentation. Main components of I and crude fat of the solid fraction were free fatty acids (FFA), triglycerides (TG) and ethyl esters of fatty acids (EtOR). Fat-by-hydrolysis of the solid fraction was mostly consisted of FFA. Since EtOR was not found in the raw materials, it seemed to be formed by yeast during the fermentation. Each fraction of FFA, TG and EtOR was shown to have characteristically different fatty acid composition, respectively. The ratio of the amount of saturated fatty acid to that of unsaturated one increased during the fermentation. Since it was shown that the yeast cultured under the alcoholic fermentation condition synthesized a large quantity of C18:0 acid, most of this acid found in I was considered to be formed by yeast during the fermentation.
社団法人日本農芸化学会の論文