Processed

Soybean Koji

S tier

Soybean koji is cooked soy inoculated and incubated until a powerful protease-rich mould mat forms. Hatcho and other bean-forward misos, plus some soy-sauce koji stages, use it so proteins break into deep umami rather than rice-sweetness. The beans should be felted white, not slimy or ammoniac. This is a savoury engine. Amazake made from soybean koji will not taste like the rice pudding people expect. Temperature control matters: too hot and you grow the wrong moulds on a protein-rich bean. Dried soybean koji is less common than rice; fresh or frozen is the serious form.