Flavor development during natto fermentation

Abstract

Flavor development during natto fermentation was examined using GC/MS analysis. Steamed soybeans were inoculated with Bacillus subtilis (natto) as a starter, fermented for 3, 7, 12, and 18 hours, and the resultant natto products were subjected to GC/MS analysis. Steamed soybeans without starter were analyzed for comparison. MetAlign and AIoutput2 software were employed for semi-Automatic GC/MS peak analysis and MS data processing to determine flavor compounds. As a result, a total of 38 volatile compounds were identified. Among these, 23 were also detected in the steamed soybean, revealing different effects during fermentation (6 compounds were reduced or disappeared during fermentation, 12 were relatively stable, and 5 were increased). Twelve flavor compounds including those constituting the major natto flavors, pyridines and branched fatty acids, were strongly induced during the late stage of fermentation.