Natto characteristics as affected by steaming time, bacillus strain, and fermentation time

Natto was made in a laboratory scale from soybean using 2 steaming times, 9 Bacillus natto strains, and 6 fermentation times. Natto characteristics in cluding color, firmness, viscosity, ammonia content, and bacteria populatio n were determined. The highest viscosity value of the final products was th e natto inoculated with B. natto "Itobiki strain"; the 2nd was natto with B . natto NRRL B-3383 strain. A higher steaming time reduced fermentation tim e and ammonia content in the final products. A combination of soaking at th e room temperature for 20 h (weight increase ratio: 2.1 to 2.3), steaming a t 121 degreesC for 40 min, inoculated with "Itobiki strain" or NRRL-3383 st rain, and fermented at 40 to 42 degreesC for 18 h was able to produce good natto products in a laboratory scale.