What You Need to Know
During fermentation, Aspergillus oryzae secretes proteases that hydrolyze soy proteins into free amino acids, especially glutamic acid, while amylases convert starches into sugars that participate in Maillard reactions. The high salt concentration (15–20 % NaCl) inhibits unwanted bacteria and stabilizes the flavor, and a small amount of alcohol (≈0.5 %) is produced by yeast activity during aging.
The Science
Primary Reaction
Proteolysis and Maillard reactions producing amino acids and flavor compounds