Storing Kombu Dashi

Dashi made without the application of heat should not be left in the refrigerator for more than 10-12 hours. After this point, the complex sugars contained in the kombu will begin to emerge into the water, giving the dashi a gelatinous texture. As this happens, it must also be expected that bacteria will begin to multiply in the dashi, as the concentration of the salt and sugars released into the dashi reach a suitable level for bacterial germination. Even if the kombu is dried to begin with, it may still contain some bacteria, and the increase in the water saturation of the kombu provides a good environment for their multiplication.