Description
The enzymatic fermentation stage where koji-inoculated soy-wheat mash undergoes proteolysis and saccharification.
Technical
Aspergillus oryzae molds produce amylases (α-amylase, glucoamylase) and proteases (acid protease, neutral protease) that hydrolyze starches into glucose and proteins into amino acids including glutamic acid. Lactobacilli (Tetragenococcus halophilus) and yeasts (Zygosaccharomyces rouxii) subsequently develop, lowering pH to 4.7-5.0.
Culinary Significance
Creates the umami foundation for soy sauce through glutamic acid production while developing complex flavor precursors like 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF).
Science
Primary Reaction
Proteolysis
Parameters
Temperature
30°C optimal
15°C to 40°C range
Time
6 months
3 months – 24 months
Equipment