清酒酵母に関する研究 : (第2報)馴養に依る醗酵力の変化
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概要
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A study was made on the possible variation of Saké-yeasts in the course of repeating the ino-culation on five sorts of Koji-extract media which contained different amount of sugar, acid (lactic acid) and alcohol. After repeating inoculation about 300 times for 4 years, their fermenting powers were determined. As the amount of yeast to be added to the fermentable medium hadnt. been constant in former methods, we made the tests in two well-defined manners, “one-fifteenth” and “fundamental” tests of fermenting powers. The numerical value of one-fifteenth was due to the ratio of “mother” to “main” mash in Saké-brewing, which was 1:15. In the method of the “fundamental” fermentation test the yeast centrifuged from a definite volume of preculture was added into the fermentable medium with the same volume as that of the preculture. The results can be summarised as follows: (1) Concerning the influence of the concentration of sugar in the preculture, it was found that the yeasts acclimatized for lower concentration had greater fermenting power than those acclimatized for higher concentration. (2) Alcohol and acid (lactic acid) had a very delicate relation with the multipli_??_ation and fermenting power of the Saké-yeasts, and the yeasts acclimatized to both alcohol and acid have generally greater fermenting power than any others. (3) It should be pointed out that similiar phenomena were sometimes found in the accli-matization of the yeast to those noted in the case of agricultural crops, where the rotation of crops is superior to the continuous cultivation of the same land. This was supposed to be caused by a certain defect of the standard sterilized Koji-extract as a nutrient medium of the yeast.
- 社団法人 日本農芸化学会の論文