It is mixed with koji (a fermentation agent) and salt to ferment, so the protein of soybean resolves to be easily digestible and large amounts of amino acid which is the source of umami (savory) are released.
これに麹や塩を混ぜ合わせ、発酵させることによって大豆のタンパク質が消化しやすく分解され、また旨みの元であるアミノ酸が多量に遊離する。