Rice Koji, Barley Koji and Soybean Koji (米麹・麦麹・豆麹)
The three classic koji bases. The grain or bean the mould grows on decides which seasoning the koji is suited to make.
| Rice koji (kome-koji) | The most versatile base. Used for most miso, amazake, shio koji, sake and sweet seasonings |
|---|---|
| Barley koji (mugi-koji) | The base of barley miso, common in Kyushu and parts of Shikoku and Chugoku |
| Soybean koji (mame-koji) | The base of soybean miso such as Hatcho miso, and of tamari-style brewing |
The naming is literal: koji takes its name from its substrate. Rice koji smells faintly sweet and chestnut-like when fresh; barley koji is nuttier; soybean koji is made only from soybeans and drives the deep, concentrated character of soybean miso.
The substrate also shapes nutrition facts on the label and allergen information: barley koji contains barley, soybean koji is a soy product, and rice koji is the usual starting point for people avoiding those ingredients - always confirm on the individual label, as blended products exist.
In shops, rice koji is sold fresh (nama), dried (hoshi) or frozen. Dried koji keeps longest and is the form most often exported.
See also
Rice misoRelated page in this guide.Barley miso
Related page in this guide.Soybean miso
Related page in this guide.
Sources: Ministry of Agriculture, Forestry and Fisheries (MAFF), 'Traditional Foods in Japan'; JAS soy sauce standards; Umami Information Center; Kikkoman official information; Wikipedia (CC BY-SA 4.0). Checked 6 November 2026.