Key Points and Detailed Methods of Fresh Mushroom Salting Technology

1. Selection of fresh mushrooms: Fresh mushrooms to be salted should be harvested at the right time, and impurities, diseased, insect-damaged and moldy parts should be removed. The caps of the fresh mushrooms are required to be intact, the roots of the fresh mushrooms should be removed, and for oyster mushrooms the clustered fruiting bodies should be separated one by one, discarding deformed mushrooms; for nameko mushrooms and lion's mane mushrooms, the aged stipes should be cut off. It is worth noting that fresh mushrooms harvested on the same day should be processed on the same day, and must never be left overnight.

2. Rinsing of fresh mushrooms: Put 0.3 kg of table salt into 50 kg of water. (Do not make it too concentrated, otherwise the mushroom bodies will turn red.) Dissolve to make a 0.6% salt solution, wash off mud fragments and other impurities on the surface of the fresh mushrooms, then rinse with citric acid solution (pH 4.5), which can significantly change the color of the mushroom bodies.

3. Blanching of fresh mushrooms: This refers to the process of boiling the mushroom bodies in dilute salt water to kill the cells. Its effect is to further inhibit enzyme activity, prevent the mushrooms from opening their caps, expel water from inside the mushroom bodies, and enlarge the stomata so that the salt water can quickly enter the mushroom bodies. Blanching should be carried out promptly after rinsing. Use a stainless steel pot or aluminum pot (mushroom bodies contain sulfur-containing amino acids, which easily combine with iron during boiling to form black iron sulfide, so an iron pot cannot be used), add 10% salt water, with a water-to-mushroom ratio of 10:4, and use a strong flame. After the salt water boils, place the mushrooms in a bamboo sieve (the amount placed should be 3/5 of the container volume), put them in together and keep shaking so that all the mushrooms are immersed in the boiling water. Remove the foam at any time. The boiling time depends on the size of the mushrooms, about 7-10 minutes, and it is best when the cut-open mushrooms have no white core and are light yellow both inside and outside. If not boiled through, they will change color during storage and may even rot. After boiling, take them out together with the sieve and immediately place them in flowing clean water to cool for 20-30 minutes. The salt water in the pot can be used continuously 5-6 times. After it has been used 2-3 times, an appropriate amount of table salt should be added each time.

4. Preparation of saturated salt water and acid-adjusting agent: Prepare water and table salt at a ratio of 10:4, and dissolve the salt with boiling water until the salt can no longer dissolve. Measure its concentration with a Baume hydrometer at about 23 degrees Baume, then add a small amount of alum and let it stand. After cooling, take the supernatant and filter it through 8 layers of degreased gauze so that the salt water becomes clear and transparent; this is saturated salt water. Store it in a dedicated vat, cover it with cloth, and then cover it with the vat lid for later use. Mix 50% citric acid, 42% sodium metaphosphate and 8% alum evenly, add to the saturated salt water, and use citric acid to adjust the pH to 3 (summer) or 3.5 (winter) to make the acid-adjusting agent.

5. Salting: The container should be washed clean, disinfected with 0.5% potassium permanganate solution, and then rinsed with boiling water. Salt the mushrooms that have been blanched, graded and drained according to the ratio of adding 25-30 kg of refined salt per 100 kg, layer by layer. First place a layer of salt at the bottom of the vat, then place a layer of mushrooms about 8 cm thick, then place a layer of salt, then a layer of mushrooms, until the vat is full. Pour boiled and cooled saturated salt water into the vat. Cover the surface with a bamboo cover mat or wooden strip cover mat, and press stones on top so that the mushrooms are submerged in the salt water. Within 3 days, the vat must be turned once, and thereafter once every 5-7 days. During the salting process, frequently measure the salt water concentration with a Baume hydrometer and keep it at about 23 degrees. If it is lower, the vat should be turned, and the mouth of the vat should be covered well with gauze and the vat lid.

6. Barreling: After salting for more than 20 days, it can be barreled. Before barreling, first take out the salted mushrooms and drain off the salt water completely. Generally, plastic barrels are used for packaging, then newly prepared acid-adjusting agent is added up to the mushroom surface. Seal the opening well with refined salt, expel the air in the barrel, and close the inner and outer lids tightly.