Description
Bacillus subtilis var. natto metabolizes soy proteins into sticky polyglutamate chains and umami-rich peptides.
Technical
The fermentation involves extracellular protease enzymes (subtilisin, nattokinase) cleaving soy glycinin and β-conglycinin into oligopeptides. Concurrently, γ-polyglutamic acid (γ-PGA) polymerizes via glutamate ligases, creating the characteristic viscous texture. Glutaminase activity generates free glutamic acid for umami.
Culinary Significance
Produces intensely savory natto with slimy strands that cling to rice. The ammonia-like aroma develops from leucine catabolism into 3-methylbutanoic acid. Traditional serving with karashi mustard and scallions balances funky notes.
Science
Primary Reaction
Proteolysis
Parameters
Temperature
°C to °C range
Above 45°C promotes unwanted Bacillus cereus
Time
24h
18h – 48h
Longer fermentation increases fibrinolytic activity
Equipment