Changes in compositions and microorganisms in dakusyu-sake brewing using the Bodaimoto method

"Bodaimoto, the oldest starter of Refined Sake, has been used for hundreds of years all over Japan. However, we noted that Bodaimoto disappeared after the development of a more useful starter, "" Sokujyomoto"", in the Taisho-Era. Recently, we discovered that Bodaimoto has been brewed to make Dakusyu-sake (a kind of Doburoku-sake) for Shinto shrines in the Nara area since the early Showa-Era. We therefore researched the production process of Dakusyu-sake and obtained information. The special feature of the Bodaimoto method is to make acidic water called Soyashimizu. Lactic acid bacteria help to make Soyashimizu while raw rice is soaking in water at a mild temperature. In the Soyashi process, lactic acid bacteria grow rapidly in the Soyashimizu water. The pH of the solution fell below four rapidly and the number of undesirable bacteria was consequently reduced. The number of yeasts in Soyashimizu increased after five days of fermentation and those yeasts were confirmed to be fermentable by TTC staining. Fermentation of Bodaimoto (seed mash) continued for six days. It contained 8.9 v/v% of alcohol, 3,500 ppm of lactic acid and 1,300 ppm of acetic acid. Fermentation of Dakusyu (main moromi mash) continued for 17 days. At the beginning of brewing fermentation of the mash was so active that the temperature of the mash rose to 35 deg C and the concentration of alcohol increased immediately. Then fermentation proceeded slowly. At the end of fermentation a considerable amount of water was added to the mash to lower the alcohol concentration. Contents of the Dakusyu-sake were as follows: Alcohol ; 11.2 v/v%, Sake-meter; -25, Acidity; 3.2, Amino acidity; 3.6. In a sensory test, the Dakusyu-sake proved delicious in spite of the low alcohol concentration, suggesting a new type of sake with a lower alcohol content."