PREPARATION OF SALT-FREE MISO AND ITS HIGH-PRESSURE TREATMENT FOR PRESERVATION

To make salt-free mise, a mixture of rice koji and boiled soybeans was saccharized at 55 degrees C for 24 hand fermented at 25 degrees C for a period of 28 days after the halophilic yeast Zygosaccharomyces rouxii IAM 12880 was added. In the salt-free mise obtained, yeast was inactivated by pressurization at 300 MPa and 25 degrees C for 30 min. Addition of NaCl to the mise had an adverse influence on the pressure inactivation of yeast; the yeast in the mise containing 5 and 10% NaCl was inactivated by pressurization at 400 and 500 MPa, respectively. An increase in ethanol concentration contained in the salt-free miso caused more effective inactivation of yeast and enzymes including proteases and amylase by high pressure treatment. Thus, the mise containing low salt can be sterilized at a lower pressure for preservation.