1999 Volume 46 Issue 5 Pages 279-284
Heat production during the fermentation of natto, a traditional Japanese food consisting of soybeans fermented by Bacillus subtilis (natto), was investigated using a commercially available calorimeter (MPC-II from Tokyo Riko Co., Ltd.). Thermograms of the fermentation of whole bean natto showed two phases of heat production, suggesting the existence of two stages of growth or metabolism, initial and secondary, of B. subtilis (natto). Some enzymes, i.e., cellulases, hemicellulases, etc., produced during the initial growth stage digest the seed coat and excrete new nutrients from the seed. These nutrients are in turn used during the secondary growth or metabolism stage of the bacteria. The rate of heat production indicating the activity of natto fermentation was largest in the range from 42 to 47°C of the temperatures examined in this study, in accordance with the temperatures (of the beans) which have been employed in the industrial natto fermentation.
