Edible Mushroom Cold Storage Methods and Introduction Notes

Shiitake mushroom production has flourished across both northern and southern regions of China in recent years. After bag-cultivated shiitake became widespread in Fujian, provinces such as Zhejiang, Henan, and Hubei successively developed bag-cultivated shiitake with success. Quick-freezing storage of shiitake has become an indispensable and important preservation technique in both production and sales. Quick-freezing storage of shiitake is simpler and more convenient than that of button mushrooms. Generally, fresh mushrooms are pre-cooled in ice water, removed and drained, then rapidly frozen in an ultra-low temperature freezer at -50 to -60°C, and afterward stored in a cold storage at -18 to -24°C. Through the "cold chain" system they reach consumers' homes. It is said that quick-frozen shiitake can be preserved for 1.5 to 2 years.

Quick-Freezing Storage of Enoki Mushroom (Flammulina velutipes)

After fresh enoki mushrooms are harvested, they are sorted and packed into special food bags, with each bag containing a fixed amount of 100 grams, 200 grams, or 500 grams. The bags are heat-sealed or vacuum-sealed, then immediately placed in a -20°C freezer for storage. The preservation period reaches over 1 year, with excellent nutrition and flavor.

Quick-Freezing Storage of Oyster Mushroom (Pleurotus ostreatus)

1. Process flow. Raw material selection → sorting and grading → blanching → cooling → draining → bagging → quick freezing → low-temperature storage.

2. Raw material selection and grading. Oyster mushroom raw materials should be fresh and intact, with normal grayish-white color, shallow cracks on the cap edge, cap diameter of 3 cm or more, and the stem cut to a length of 1 cm. Remove rotten and deteriorated mushrooms and impurities from the growing substrate. Rinse the mushrooms clean under running water, separate clustered mushrooms into individual ones, and grade them into large, medium, and small based on cap diameter.

3. Blanching and cooling. Add clean water to the blanching tank, with the water amount about 2/3 of the tank capacity, and add 0.05% to 0.1% citric acid to the water. After the blanching solution is heated to boiling, pour the oyster mushrooms into the tank for blanching, with the amount of oyster mushrooms added being 20% to 30% of the blanching solution. Gently stir the mushrooms to ensure even heating. The blanching solution temperature should be maintained at about 95°C, and blanching generally takes 5 to 8 minutes. Immediately after blanching, cool rapidly in clean cold water. After cooling, place the mushrooms into clean gauze bags and dehydrate in a centrifuge.

4. Bagging and quick freezing. According to the graded sizes, place the oyster mushrooms into clean plastic bags, 500 grams per bag. After sealing, send the oyster mushrooms into the quick-freezing chamber and rapidly freeze at a low temperature of -25 to -30°C.

5. Low-temperature storage. After quick freezing, the oyster mushrooms are packed in bags into cartons, tightly packaged, and placed in a -18°C low-temperature warehouse for storage until consumption.