Toxins will be produced if soaked for a long time.

If the indoor temperature is above 20°C, especially at high temperatures in summer, fungus will deteriorate very quickly. When the fungus is soaked in water for more than 8 hours, the bacteria caused by the deterioration may produce biotoxins in a dose sufficient to cause a poisoning reaction. Therefore, it is recommended that you do not eat black fungus soaked in water for more than 8 hours in summer to prevent poisoning.