When it comes to preserving mushrooms, the first thing that comes to mind is low temperature. Yes, keeping fresh at low temperature is the most common method. Cryopreservation can inhibit the activity of microorganisms and reduce the activity of decomposing enzymes, but the premise is that cells cannot be destroyed. The principle of rapid freezing is to use high-speed cooling to cross the dangerous temperature zone (-5 ~ 0 degrees) for ice crystal growth, so that it is too late to form ice crystals that can kill cells. Experiments show that the faster the thawing speed, the higher the cell survival rate. This method can be used for long-distance transportation. Through quick freezing, the temperature of Tricholoma matsutake is lowered to-30℃ for 4 hours, and then raised to -20℃ for storage (because the lower the storage temperature, the higher the equipment requirements and the higher the cost). This method can be preserved for more than three years without deterioration! This method of ice preservation is suitable for short-distance transportation. Fill the foam box with ice cubes, relax the velvet in the middle and seal it with tape. Refrigerator is the most widely used in the family. The temperature is controlled at 1 ~ 5℃ and the relative humidity is 85% ~ 95%, and it can be stored for 10 day. The second preservation method of Tricholoma matsutake is familiar to everyone: salting preservation. The salt solution with concentration of 20% can produce hypertonic pressure below 120 atmospheric pressure, which separates the plasma membrane of microorganisms, shrinks protoplasm and produces physiological drying. At the same time, it can also form an anaerobic environment, making microorganisms unable to survive. Interestingly, whether it is frozen or pickled, Tricholoma matsutake should be scalded with hot water before preservation (scalding at 70℃ for 5 ~ 10 minutes), because high temperature can inactivate enzymes in Tricholoma matsutake, reduce its metabolism, maintain its primary color and play a bactericidal role. The most famous feature of Tricholoma matsutake is its aroma, and the aroma of fresh Tricholoma matsutake will disappear within 5 ~ 6 hours after picking. Japanese patentees found that the aroma of Tricholoma matsutake was not easy to be lost when it was stored at -24℃, but when the temperature dropped below -25℃, the aroma would drop sharply. The specific operation is: put the dried Tricholoma matsutake into the cold storage at -25 ~-30℃, and control the temperature in the cold storage at -20 ~-24℃ after the central temperature of Tricholoma matsutake reaches -22 ~-24℃. This is its core step. It is said that the aroma of Tricholoma matsutake will not be scattered for months or even half a year, which means that even in winter and spring, you can eat fresh Tricholoma matsutake with overflowing aroma.