Contaminated by mold. Poria cocos will be contaminated by mold during drying and frying, resulting in tiny mildew spots on the surface or inside of Poria cocos. In the frying process, if the frying time is too long or the temperature is too high, the mold in Poria cocos will ferment to produce peculiar smell, giving people a moldy taste. Therefore, when purchasing Poria cocos, we should choose products with clean appearance and no mildew, and control the frying time and temperature to avoid odor.