Cultivation of Saccharomyces cerevisiae using Defatted Rice Bran Hydrolyzed in Near-critical Water as a Culture Medium

s − The hydrolysis of defatted rice bran using near-critical water was performed, and the feasibility of consequent hydrolyzate as a growth medium was investigated by the cultivation of Saccharomyces cerevisiae. The near-critical water hydrolysis was carried out through a series of batch experiments, and the contents of total carbohydrates, disaccharides, and monosaccharides, total organic carbon (TOC), total nitrogen (TN), pH of products were measured. The growth rate of Saccharomyces cerevisiae was measured with optical density. The yield of total carbohydrates, TOC, and TN increased with temperature below 240 oC, however, decreased above 240 oC. The decrease of yields above 240 oC was caused by the formation of organic acids, and it agreed with the change of pH of products. The yield of glucose was a maximum at 200 oC and it decreased dramatically at higher temperature. The growth rate of Saccharomyces cerevisiae cultivated in the hydrolyzate was similar with that in the commercial medium under certain conditions. The growth rate was correlated with the content of glucose in hydrolyzate.