Miso Fermentation with S. Rouxii

HESSELTINE, C. W. (Northern Regional Research Laboratory, Peoria, Ill.), AND K. SHIBASAKI. Miso. III. Pure culture fermentation with Saccharomyces rouxii. Appl. Microbiol. 9:515-518. 1961.-Excellent miso has been prepared with soybean grits inoculated with a pure culture of Saccharomyces rouxii strain NRRL Y-2547. Pure culture inoculum of this osmophilic yeast was prepared by growing the culture in aerated flasks on a yeast extract medium with a salt concentration equal to that used in the manufacture of miso. It has also been found possible to make miso from whole beans with the above culture. The advantages of pure culture fermentation in producing miso are discussed. Miso is a Japanese food prepared by fermentation of mold rice, soybean, and salt. 2 This is a laboratory of the Northern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture. As previously described (Shibasaki and Hesseltine, 1961c), the manufacture of miso is a process involving two separate and distinct fermentations. The first involves the aerobic pure culture fermentation of rice with selected strains of Aspergillus oryzae (Ahlburg) Cohn to prepare koji (mold rice) as a source of enzymes and nutrients for the second fermentation-the fermentation of mold rice, salt, and soybeans. In the second fermentation the inoculum used is a suitable sample of good miso from an earlier fermentation. Such a mixed inoculum has two obvious disadvantages: 1) Contaminating microorganisms are carried from one fermentation to the next. 2) Since most types of miso require months to ferment, followed by an aging period, it is apparent that the proper microorganisms for the fermentation become reduced in number and vigor; hence, a longer period is required for them to grow actively and multiply. Since most modern fermentations are started with pure cultures, an obvious improvement in the manu19611 a51 on Jne 4, 2017 by gest ht://aem .sm .rg/ D ow nladed fom C. W. HESSELTINE AND K. SHIBASAKI fiacture of miso would be the use of a pure culture starter. Several different organisms might be mixed together at the time of inoculation if a mixed culture fermentation