Natto Characteristics as Affected by Steaming Time, Bacillus Strain, and Fermentation Time

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