1) In order to restore the degenerated or weakend sporulation ability of the saké yeast, the following procedure is found preferable. Using the koji extract which is not sterilized by heat but freed from microörganisms by filtering with the Schott's G 5 filter, the inoculations are repeated 7-8 times each at 2-3 days' interval, the more 2-3 times each 7 days'(or longer) interval.
2) The staining percentage of the yeast with Methylene blue increases up to its maximum value on about the 7 th day after inoculation and then decreases gradually.
3) The optimum temperature of the preculture to secure the highest sporulation percentage of sake yeasts lies near the maximum temperature of their multiplication.
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