Selection of strains producing soy sauce and their fermentation conditions

This paper reports the investigation of different enzyme systems for soy sauce production: spergillus oryzae JPDQ1, Aspergillus oryzae JPW in Japan and Aspergillus oryzae AS3.951 in China. It shows that three kinds of strains can produce αamylase, saccharifying amylase, cellulase, pectinase, acid proteinase, and neutral proteinase in concentrated soy sauce koji and white soy sauce koji. By comparison, we conclude that JPW is a better strain for producing white soy sauce and JPDQ1 is a better strain for producing concentrated soy sauce. By partially studying the physiological characteristics of soy sauce yeast, we find that the effect of salt concentration on the growth of soy sauce yeast is obvious. We suggest that the salt concentration in fermentation of soy sauce should not be over 3?mol/L and the better one is below 2?mol/L. The optimum growth pH of soy sauce yeast is from 4.5 to 5.5.