Detailed Explanation of Key Points of Chemical Preservation Techniques for Edible Fungi

Chemical substances that are harmless and non-toxic to humans and livestock are used to soak or spray the surface of fungi, so as to extend their freshness. Chemical preservation has many advantages, such as simple method, low cost input, and a high degree of freshness retention.

1. Sodium chloride (i.e. table salt) preservation: Freshly harvested oyster mushrooms, Phoenix mushrooms, etc., after being trimmed, are soaked in 0.6% salt water for about 10 minutes, drained, and then put into plastic bags for storage, which can keep them fresh for 5-8 days.

2. Sodium metabisulfite spray preservation: Freshly harvested oyster mushrooms are spread on a clean cement floor, and a 0.15% sodium metabisulfite aqueous solution is sprayed onto the mushroom bodies, while turning the mushrooms so that the solution adheres evenly. The fresh mushrooms are packed in plastic bags, sealed immediately, and stored in a cool place. At 10-25°C, they can be kept fresh for 8-10 days. Before eating, rinse with clean water.

3. Dilute hydrochloric acid soaking preservation: Fresh straw mushrooms are trimmed, rinsed with clean water, and air-dried, then put into a vat or bucket, and a 0.05% dilute hydrochloric acid solution is added, with the soaking level preferably covering the mushroom bodies. Cover the gap or the mouth of the bucket. The acid solution can inhibit the acid activity of straw mushrooms and the growth and reproduction of microorganisms.

4. Rice soup film preservation: To the thin rice soup produced when cooking rice, add 1% soda ash or 5% baking soda, stir well after dissolving, and cool to room temperature. Soak the harvested fresh mushrooms in the rice soup alkaline solution for 5 minutes, then remove them and place them in a cool, dry place. At this time, a thin film of rice soup forms on the surface of the mushrooms to isolate air, and they can be kept fresh for 72 hours.

5. Ascorbic acid preservation: After enoki mushrooms, shiitake mushrooms, straw mushrooms, etc. are harvested, a 0.1% ascorbic acid solution can be sprayed onto the fresh mushrooms, and they are put into non-iron containers. They can be kept fresh for 3-5 days, and their freshness and color basically do not change.

6. Sodium chloride and calcium chloride mixed solution preservation: Use 0.2% sodium chloride plus 0.1% calcium chloride to make a mixed soaking solution, and soak the freshly harvested mushrooms in the mixed solution. It is best to cover them with a bamboo mat and add a weight so that the fungi are immersed below the liquid surface for 30 minutes. At 15-25°C, they can be kept fresh for about 5 days, and at 5-10°C, they can be kept fresh for more than 10 days.

7. Preservation liquid soaking preservation: Prepare a preservation liquid with 0.05% ascorbic acid and 0.02% citric acid. Soak the fresh mushrooms to be preserved in the preservation liquid for 10-20 minutes, remove and drain the water, and pack and seal them in plastic bags. With this method, the mushroom bodies look as fresh as new, and the rate of whole mushrooms is high.

8. B9 preservation: The chemical name of B9 is N-dimethylaminosuccinamic acid, which is a plant growth retardant. Soak fresh mushrooms in a 0.1% aqueous solution for 10 minutes, take them out, drain, bag, and seal. Keep them fresh at 5-25°C, and they can be kept fresh for more than 15 days. It is suitable for the preservation of mushrooms, shiitake mushrooms, oyster mushrooms, enoki mushrooms, and other fungi.

9. Hormone preservation: Soak fresh mushrooms in a 0.01% 6-aminopurine solution for 10-15 minutes, then take them out, drain, bag, and store.

10. Chlormequat preservation: Soak freshly harvested mushrooms in a solution containing 20 milligrams of chlormequat per kilogram of solution, which can extend the freshness period of fresh mushrooms.

11. Medical stone preservation: Put fresh straw mushrooms into a plastic box, submerge the mushroom bodies with medical stone water, and keep them fresh at a low temperature below 0°C. The freshness period can reach 70 days, and the amino acid content is not much different from that of fresh mushrooms, while the color and taste are both relatively good.