Shio Koji Extract

Shio koji (塩麹) is a traditional Japanese fermented seasoning made by combining rice koji (Aspergillus oryzae cultivated on steamed rice), salt (typically around 12–15% of the koji weight), and water, then aging at room temperature for approximately 7–14 days. The resulting paste / liquid is rich in koji enzymes (proteases, amylases, lipases), free amino acids, and salt — used as an all-purpose marinade, tenderizer, and salt substitute.

Aspergillus oryzae produces multiple protease enzymes (acid, neutral, and alkaline) during koji fermentation. When shio koji is applied to meat or fish, these proteases hydrolyze surface and shallow-tissue collagen and muscle proteins into smaller peptides and free amino acids. The result is mechanical tenderization plus a marked umami increase from generated free glutamate, aspartate, and other amino acids — typically achievable in 30 minutes to overnight depending on cut.

Yes. Aspergillus oryzae has long been recognized as safe for food use (it is the koji-mold used in soy sauce, miso, and sake brewing) and is on the European Food Safety Authority's QPS list and on FDA's GRAS-equivalent recognition for traditional fermentation use. Industrial shio koji production uses standardized koji strains, controlled fermentation, and salt levels that suppress pathogenic microbial growth. Standard food safety and HACCP protocols apply.

Shio koji can be used as a partial salt substitute in cooking — a typical 1:1 weight substitution of shio koji for salt delivers approximately 12–15% of the salt amount the table salt would have provided, since shio koji is itself only 12–15% salt. The compensating umami from koji-released amino acids gives perceived savoriness comparable to higher-salt versions. Reduced-salt cuisine and some sodium-reduction product reformulation literature in Japan reference shio koji.