Writer: Yumiko Ishimaru
Drying fresh shiitake increases its vitamin-D, which we need to absorb calcium. This also increases its umami substances much more. Also, dried shiitake is an excellent preservative food. You can boost the vitamin-D level in dried shiitake by exposing them lamella side up in sunlight again before rehydrating them.
Here is a trick to make dashi from dried shiitake. I was amazed at how much of a difference this small step could make. I learned it when I just started studying about “dashi”.
Rehydrate them, and put dried shiitake and water in an enclosed storage bag. Let it soak in the refrigerator overnight. This means I use cold water. It takes one night to make dashi. There is science in the step. You know why? Using cold water to rehydrate dried shiitake slowly brings out strong umami flavors by increasing a umami substance named guanylic acid.
I don’t have to add any procedures. Just a bit of time improves the taste better. It makes me feel like a great cook. A microwave oven cannot do this trick.
Dried shiitake are weak to humidity like other dried food. Once the package is opened, store them in a lower temperature in the refrigerator. You can store them in a room temperature if you put them in a clean container with a desiccant.
Let me repeat, expose your home-stored dried shiitake in the sun before you use them.. haha.