Which Japanese seasoning is made by fermenting soybeans with salt and koji? The seasoning is miso.
Miso is a thick, savory paste made from soybeans, salt, and kōji, a culture usually involving the mold Aspergillus oryzae. Producers may also include rice, barley, or other grains. During fermentation, kōji enzymes break down starches and proteins, producing the amino acids and compounds associated with miso’s deep umami flavor.
Miso varieties differ in color, sweetness, saltiness, grain composition, and aging time. White miso is generally milder and sweeter, while darker red miso tends to have a stronger, more robust flavor, though these labels are not perfectly standardized. Fermentation can last from days to several years depending on the style.
Miso is best known in miso soup, where it is blended with dashi, but it is also used in marinades, sauces, dressings, pickles, and spreads. It should not be confused with soy sauce: both use fermentation, but miso remains a paste, while soy sauce is a liquid extracted from a fermented mash. Miso is salty, so it is usually added with other seasoning in mind.