Description
Dual-stage fermentation process where koji enzymes convert rice starches to sugars before acetic acid bacteria transform them into vinegar.
Technical
Aspergillus oryzae secretes amylases (α-amylase EC 3.2.1.1 and glucoamylase EC 3.2.1.3) to hydrolyze rice starch into glucose, followed by Acetobacter pasteurianus oxidizing ethanol to acetic acid (CH3COOH) via membrane-bound alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH).
Culinary Significance
Produces a mellow, umami-rich vinegar with subtle sweetness, essential for sushi rice, pickling, and salad dressings in Japanese cuisine.
Science
Primary Reaction
Ethanol fermentation
Parameters
Temperature
32°C optimal
28°C to 38°C range
Time
2-3 months
3 weeks – 6 months
Equipment
Wooden koji trays (traditionally cedar)Cotton cloth coversEarthenware fermentation vessels