Miso is a versatile Japanese ingredient. It can be mixed with dashi to make miso soup or used as a marinade to add complexity to meat, fish, and vegetables. Its deep and rich savoriness also elevates the flavor of desserts with a tangy kick.
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How Is Miso Made?
Miso can be made from a variety of grains; but most common types are made mainly of rice, soybeans, and barley. To kick off the fermentation process, koji mold is spread all over the cooked grains; these “hungry” molds then consume the grains and convert the starch in the grains into alcohol.
The alcohol helps fend off bacteria growth and prevents spoilage. However, the amount of alcohol is small and varies from one style of miso to the other.
How Long Does Miso Last after Opening?
There are more than 1,300 varieties of Japanese miso. Depending on the preparation and style, an opened jar of miso can stay fresh anywhere from six months to even years if stored properly, said Emiko Davies, author of Gohan: Everyday Japanese Cooking (2023). She added that the flavor of miso changes and that it “tastes better over time.”
However, if you discover mold or the miso tastes strange, you should toss it out.
The general rule of thumb is the paler the color, the shorter shelf life. Dark miso is typically aged for longer before being sold. The appearance of the miso may change after opening, due to exposure to air.
How Should You Store Miso?
It’s best to store miso in the refrigerator after opening to ensure best quality. Davies stores hers with a little piece of parchment paper cut to the size of the miso jar (or container) on top. This reduces air contact and helps prevent a crust of hardened paste from forming on top of the miso paste.
