Effect of roasting and puffing on amino acid contents of Bacillus subtilis-fermented beans

In this study, the effect of introducing roasting and puffing on the profile of total amino acids in three types of beans—soybean, chickpea, and fava bean—fermented with Bacillus subtilis was evaluated. The established condition for roasting was 120°C for 30 min and that for puffing was 588 kPa based on the extent of water absorption after sample treatment. Roasting or puffing alone did not significantly affect the amino acid composition of the three types of beans. However, fermentation decreased the relative content of arginine, aspartic acid, glycine, serine, and threonine and increased that of glutamic acid compared with that in unprocessed beans. Roasting and puffing combined with fermentation mitigated the reduction in lysine and threonine contents caused by fermentation and showed a synergistic effect in increasing the contents of phenylalanine, leucine, and valine. The changes were similar regardless of the bean type. The combined processing on the three types of beans significantly increased the total proportion of essential amino acids in the beans.