Description
Japanese koji cultivation is a controlled biological fermentation of Aspergillus oryzae on sterilized substrates at 30–35 °C and 80–90 % RH for 48–72 h to maximize α‑amylase and protease production.
Technical
During incubation, Aspergillus oryzae secretes α‑amylase, converting starches into maltose and glucose, while proteases hydrolyze proteins into free amino acids such as glutamic acid. The fungal metabolism also generates organic acids that lower pH to ~5.0, suppressing bacterial growth. The resulting enzymatic activity establishes the flavor precursors for sake, miso, and soy sauce.
Science
Primary Reaction
Starch → glucose/maltose + Protein → amino acids (e.g., glutamic acid)
Sensory Profile
Aroma ()
earthynuttyumamisweetmoldyfermentedmushroom-likecaramelizedtoasted grainlightly floral