Salt-free miso fermentation using ethanol, sugars, and polyols

Steam-cooked soybeans mixed with rice koji (2:1, w/w) were ground into a fine paste, combined with NaCl or sucrose, and supplemented with ethanol for mise fermentation at 28 degrees C for 8 wk. In products containing the same concentrations of NaCl and sucrose, proteolytic activities decreased with an increase in ethanol concentration. At the. same level of ethanol (7.5% or 15%), protein hydrolysis was highest in products containing 12.5% sucrose and 0% NaCl and lowest in products containing 0% sucrose and 12.5% NaCl. NaCl enhanced and sucrose reduced the effects of ethanol on inhibition of koji proteases. A salt-free fermentation was achieved using 15% ethanol and 12.5% sucrose. When sucrose (12.5%) was substituted by glucose, fructose, sorbitol, or glycerol and supplemented with 15% ethanol, prevention of protease inactivation by ethanol was similar to that with sucrose.