Preparation and improvement of koji and moto for sake making

• Main Authors: Chiu-Lin Huang, 黃秋霖
• Other Authors: Chin-Shuh Chen Ph. D.
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/34444938841197271159

碩士 === 國立中興大學 === 食品科學系 === 90 === Sake, which wins popularity in Taiwan in recent years, is the traditional alcoholic beverage of Japan. The sake is a kind of rice wine which is made from polished rice, rice-koji, yeast starter（called moto）and water. In sake brewing, both saccharification and fermentation proceed simultaneously in the fermentation mash at 10 to 15℃ for 30 days. The alcohol content of sake is about 15-16﹪（v/v）or higher. The preparation of rice-koji, and the conditions for making yeast starter were determined in this study. In addition, determination of proper methods for dehydrating rice-koji and yeast starter, and the storage stability of dehydrated rice-koji and yeast starter were also investigated. 　　The soaking of polished rice with water at 25℃ for 12 h facilitated the subsequent cooking of rice, the moisture content of the swollen rice after soaking was 31.6﹪. The optimal condition for koji-making was determined as：The cooked rice inoculating with Aspergillus oryzae was incubated at 30℃, 90-95﹪RH, with proper aeration for 2 day. The amylase and protease activities of rice-koji were 95 and 0.8 U/ml, respectively. The optimal condition for preparing yeast starter was：Saccharomyces cerevisiae grown on the rice-koji broth was cultivated at 25℃ with shaking at 150 rpm for 2 days, the final viable count obtained was 1.7×108 CFU/ml. After examing the dehydration of rice-koji and yeast starter by freeze-drying, cold air or hot air drying methods, it was found that the enzymatic activities of dehydrated rice-koji were little affected by drying methods. However, the viability of dehydrated yeast starter prepared by freeze-drying was highest among those prepared by other methods. The viable count of a freeze-dried starter after rehydration was about 7.1×106 CFU/ml. The dehydrated rice-koji and yeast starter were stored at 4, 15 and 30℃. The amylase activity of the freeze-dried rice-koji remained constant when storing at 4℃ for 2 weeks, while the protease remained active if it was stored at 4 or 30℃. The amylase of the cold air dried rice koji was stable when it was stored at 4 or 15℃, while protease remained active at 4 or 30℃. The amylase was stable at 4 or 15℃ for a hot air dried rice koji; however, its protease activity was also stable at 15 or 30℃.