Many people discard the water used to soak dried shiitake mushrooms, but this actually leads to a significant waste of nutrients.
Li Changping, Deputy Chief Nutritionist at Beijing Hospital of the National Health Commission, explains that during the soaking process, some nutrients from dried shiitake mushrooms partially dissolve into the water, including water-soluble vitamins like B vitamins and polysaccharides, which have immune-boosting and anti-tumor properties.
In fact, as long as the dried shiitake mushrooms are cleaned before soaking, the soaking water can be fully reused.
For example, when making a soup with shiitake mushrooms, you can cook them together with the soaking water, making the broth more fragrant and flavorful, and more nutritious. Additionally, some people like to steam the shiitake mushrooms before cooking them in dishes, such as in a shiitake mushroom and bok choy stir-fry. The water from steaming the mushrooms should not be discarded; it can be used for thickening the sauce.
During interviews, some nutrition experts were also found to drink the shiitake soaking water directly, saying it is not unpleasant to taste. However, it is important to wash the mushrooms before soaking, preferably using purified water, mineral water, or cooled boiled water. The soaking water might contain some impurities, so you can either strain it slightly or let it settle in a bowl for a while, then use the clear liquid on top.
Some people use various tricks when soaking dried shiitake mushrooms, believing it makes the process faster and more effective, such as adding a small amount of sugar, which is a popular quick-soaking method. In reality, dried shiitake mushrooms can generally be rehydrated well with warm water. Sugar's main role is to remove any unpleasant odor, so it is unnecessary when soaking shiitake mushrooms. Moreover, it can easily diminish the unique flavor of the mushrooms themselves.