How long can black fungus be soaked before it's no longer safe to eat?

Aug 29, 2025 Source: Cainiu Health

Dr. Yu Yongchao

Introduction

Under normal circumstances, the duration for soaking black fungus before it becomes unsuitable for consumption should be determined based on the soaking temperature. In a room temperature environment of 20°C to 30°C, soaking should not exceed 4 hours; in high-temperature environments above 30°C, soaking should be limited to within 2 hours; when soaked in a refrigerator under cold storage, the time can be extended to about 12 hours. Black fungus soaked beyond the corresponding time limits is not recommended for consumption.

Generally, the duration for soaking black fungus before it becomes unsafe to eat depends on the soaking temperature. In a normal environment of 20°C to 30°C, soaking should not exceed four hours; in high-temperature conditions above 30°C, the soaking time should be limited to within two hours; when soaked in a refrigerator's cold environment, the soaking time can be extended to about 12 hours. Black fungus soaked beyond the corresponding time limits is not recommended for consumption. Detailed explanations are as follows:

At normal temperatures of 20°C to 30°C, soaked black fungus easily breeds Pseudomonas cocovenenans. The toxins produced by this bacterium accumulate as soaking time increases, and after more than four hours, these toxins may pose health risks and cannot be destroyed by cooking. Bacterial growth accelerates at higher temperatures, so the soaking time should be shortened to two hours to avoid significantly increased risks. Cold storage can inhibit bacterial growth, thus allowing the soaking time to be extended to about 12 hours, although bacterial growth may still occur after exceeding this time. To avoid safety issues, soaking time should be controlled according to ambient temperature, and the soaked fungus should be promptly rinsed and cooked.

If the black fungus develops an unusual odor, becomes abnormally soft and mushy, or feels sticky on the surface, it should be discarded immediately and not consumed, even if the recommended soaking time has not been exceeded.

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Can you eat black fungus (wood ear mushroom) the next day after it has been soaked overnight?

Under normal circumstances, whether木耳 (wood ear mushrooms) can be consumed overnight mainly depends on the storage conditions and the condition of the mushrooms themselves. When soaking wood ear mushrooms, use clean cold or warm water, avoid soaking them at room temperature for extended periods, and promptly wash and cook them after soaking. Any leftover cooked wood ear mushrooms should be sealed and refrigerated, and stored for no more than 24 hours. Carefully inspect the condition of the mushrooms before consumption, and discard them immediately if their safety is in doubt.

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Are dried black fungus that have been stored for several years still edible?

Under normal circumstances, whether aged dried black fungus (wood ear) that has been stored for several years is still edible depends on the specific storage conditions and the current state of the fungus. When purchasing dried black fungus, choose according to actual needs and avoid buying and stockpiling excessive amounts at once. During storage, ensure it is kept in a sealed container or sealed bag in a dry and well-ventilated area, away from water sources and heat sources. Carefully inspect the condition of the dried fungus before consumption, and use sufficient warm water for soaking.

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What to Eat to Lower Blood Pressure

Under normal circumstances, patients with hypertension can choose to eat foods such as celery, bananas, oats, black fungus (wood ear), and garlic. They may also take antihypertensive medications such as amlodipine maleate tablets, metoprolol tartrate tablets, hydrochlorothiazide tablets, nifedipine controlled-release tablets, and captopril tablets as directed by a physician. In addition to controlling blood pressure through dietary adjustments, maintaining a healthy lifestyle can also help achieve the goal of lowering blood pressure.