Wood-ear mushrooms: rehydrate safely before cooking

Rinse, soak and refrigerate when needed

Hong Kong’s Centre for Food Safety advises rinsing dried mushrooms under clean running water and soaking in a clean container. Keep room-temperature soaking to no more than 2 hours; use the refrigerator when a longer soak is needed. Soak only the amount you plan to use and cook promptly after rehydration. [1]

Do not rescue a suspect soak by boiling

Improper soaking of black fungus can permit production of bongkrekic acid. CFS describes this toxin as heat-stable and not removable by washing. Discard mushrooms with slime or abnormal odor, and do not use a long, warm soak on the assumption that later cooking makes everything safe. [2][1]

Follow the package for the cooking step

Imagine a recipe calling for overnight soaking. Refrigerate that soak rather than leaving it on the counter, then follow the product’s cooking directions in the intended soup or stir-fry. Rehydration softens the food; it is not the same process as cooking or sterilizing it. [1]

Hypothetical example — apply the method to the identified food
Situation	Practical choice
Long soak	Refrigerate
Slime or unusual odor	Discard
Unsafe handling	Boiling is not a universal rescue

Wood-ear mushrooms: rehydrate safely before cooking — original article outline diagram — Original editorial diagram of this article’s sections; no product photograph or clinical finding is depicted.

Sources for this article

Soaking Mushrooms and Food Safety
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.
Black Fungus Soaked Improperly May Produce Toxic Bongkrekic Acid
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.