Prevention and control of diseases of edible fungi, preservation, storage and processing of edible fungi

The fresh edible fungi picked are easy to decay and deteriorate at room temperature, and they are also easy to be damaged in the process of packaging and transportation, reducing the quality and causing losses. Edible fungi should be sold freshly in the peak production season, and fresh-keeping and storage must be done in order to collect and process edible mushroom products in the hot season. In order to regulate and enrich the market supply of edible fungi and meet the needs of domestic and foreign markets, it is necessary to do a good job in the processing of edible fungi. This paper introduces the most commonly used fresh-keeping, storage and processing methods of edible fungi.

(1) fresh-keeping and storage method

1. Cold storage: temperature is the most important factor affecting the respiration of agricultural products. Within 5-35 ℃, when the temperature increased by 10 ℃, the respiratory intensity increased by 3 times, resulting in a higher ambient temperature. However, the cold storage temperature should not be too low, usually controlled between 0 to 8 ℃. Cold is most commonly used in production. Salt or calcium chloride is added to the ice and the ice is placed on top of the stored edible fungus.

2. Controlled atmosphere storage: the principle is to reduce the concentration of oxygen and increase the concentration of carbon dioxide, thus inhibiting respiration. When the oxygen is less than 1%, it can inhibit the opening of the edible fungus, and stimulate the opening of the umbrella at 5%; a high concentration of carbon dioxide can inhibit the opening of the umbrella, but too high concentration will promote the anaerobic respiration of the edible fungus, resulting in toxicity. Atmosphere control method: (1) put the edible fungus into a transparent container and let it naturally reduce oxygen; (2) artificial oxygen reduction method, that is, filled with carbon dioxide and nitrogen. The effect of the combination of controlled atmosphere and cold storage is better.

3. Radiation treatment: γ-rays emitted by 60 cobalt or 137 palladium are used as radiation sources to treat edible fungi, which can ionize the water and other substances in the body and produce free radicals or ions, which can effectively restrain the opening of umbrellas and delay the discoloration process of bacteria. kill or inhibit the activities of spoilage microorganisms and pathogens, so as to play a fresh-keeping effect, combined with cold storage is better. The suitable radiation dose is 200000 rads.

4. Plant hormone treatment: some hormones can inhibit the respiration of edible fungi, delay senescence and prolong the preservation time; some hormones can also inhibit umbrella opening. The available hormones are: ccc, 2.4murd, mh, indoleacetic acid (iaa), naphthylacetic acid (naa), n-dimethylaminosuccinamide. The concentration varies from several to several hundred ppm.

(2) Common processing methods

1. Dry processing: the drying process is the evaporation process of the water contained in the edible fungus. When the edible fungus comes into contact with the dry and hot air, the surface water radiates to the external environment, forming a gradient difference of water content from the inside to the outside. The greater the gradient difference, the faster the moisture moves outward, and vice versa, until the internal and external water content is the same, the movement of water stops. Drying is a widely used method of processing and preservation, and not all edible fungi must be dried. For example, the fresh taste and flavor of dried mushrooms are not as good as fresh mushrooms; fresh mushrooms are generally better than fresh mushrooms; although Flammulina velutipes can be dried, they should be steamed in the pot for 10 minutes before drying; and shiitake mushrooms, black fungus and Tremella fuciformis are mainly dried. One method of drying is to dry the fresh mushrooms (ears) thinly on the Reed or bamboo curtains and put them in the sun to dry. Pay attention to turning them frequently and operate them carefully to prevent damage. In general, fresh mushrooms can be dried on two sunny days, put into plastic bags and quickly sealed for storage. Another method is drying, put the fresh mushrooms in the oven, cage or drying room, with electricity, charcoal fire or far-line heating drying, the temperature is kept at 60-65 ℃, the temperature fluctuation is not more than 7 ℃. If the drying room is used to dry, the inlet and outlet should be opened every 5-6 hours for ventilation and dehumidification, and the appropriate time is 10-15 minutes. Dried and bagged for storage.

2. Pickling and processing method: put the edible fungus into the concentrated solution of high concentration of salt, and the high osmotic pressure produced by the salt makes the microorganisms carried inside and outside the edible fungus in a physiologically dry state, and the protoplast shrinks, although these microorganisms are not killed, but they can not move, so as to ensure that the edible fungus will not rot for a long time. There are mainly mushrooms, Pleurotus ostreatus, slippery mushrooms, hericium Erinaceus using curing processing method. The specific processing steps are as follows:

The main results are as follows: (1) the selection of raw mushrooms: they should be harvested at the right time, remove impurities, get rid of mildew and fresh mushrooms damaged by diseases and insect pests. The base of the mushroom should be removed, the clumps of Pleurotus ostreatus should be separated one by one, the aging part of the stalk base should be cut off, and the hard root of the mushroom should be cut off.

(2) pre-cooking: soak the edible fungus in 5%-10% refined salt water, boil in a pot for 5-7 minutes, remove and filter dry.

(3) salinization: according to the proportion of 50 kg edible fungus 12.5 to 15 kg, first put a layer of salt at the bottom of the cylinder, add a layer of pre-cooked edible fungus, and then put salt, so repeatedly, until the tank is full. Pour the boiled and cooled saturated salt water into the tank, cover and press the edible fungus so that it is completely immersed in the salt water, and at the same time add the prepared adjustment solution to make the ph of the saturated salt water about 3.5

(4) Management: a rubber tube should be inserted into the cylinder and inflated 2 or 3 times a day to circulate the salt water up and down. Turn the tank once in 10 days and marinate in 20 days.

(5) barrel: after pickling, the bucket can be taken out and stored. The bucket should be filled with saturated salt water, and the ph value should be adjusted to 3.5 at the same time.

3. Canning and processing method: the fruiting body of edible fungi is sealed in a container, and after high temperature treatment, most of the microorganisms are killed, and at the same time, the invasion of external microorganisms is prevented, so as to obtain long-term preservation of edible fungi at room temperature. All edible fungi can be canned, but the most processed are mushrooms, straw mushrooms, Tremella fuciformis and hericium Erinaceus. There are eleven processes in the whole process:

(1) the choice of canned containers. Generally there are tinplate cans, glass bottles and soft cans. Suitable containers can be selected according to the production process and market demand.

(2) selection and treatment of raw mushrooms. The edible fungus is required to be fresh, free from diseases and insect pests, normal color and complete umbrella. The fungal stalk should be cut flat and the length of the handle should not exceed 0.8 cm.

The selected edible fungi are poured into 0.03% sodium thiosulfate solution, washed away from the mud and sand, removed, and then poured into 0.1% sodium thiosulfate solution with appropriate amounts of vitamins c and e.

(4) heat and boil. First put tap water in the container, heat to 80 ℃, add 0.1% citric acid, bring to the boil, pour the edible fungus into boiling water and precook for 8 minutes and 10 minutes, constantly removing the floating foam.

(5) grading. After pre-cooking, take out the edible fungus and cool it in cold water and grade it according to size.

(6) canning. Each can should not be too full, leaving a gap of 8 mm to 10 mm from the lid. Usually 500 grams of empty cans should be filled with 240 grams 250 grams of edible fungus and 180 grams 185 grams of soup. Soup formula: 97.5kg of water, 2.5kg of refined salt, 50g of citric acid, heated for more than 90 ℃ and filtered with gauze. When the soup is injected, the temperature is not lower than 70 ℃.

(7) exhaust. The most commonly used method is to heat the exhaust, that is, the can is placed under 8690 ℃ for 8min for 15 minutes to remove the air in the can.

(8) sealing cans.

(9) sterilization. Canned edible fungi are usually sterilized by high pressure steam. The temperature of sterilization is different for different edible fungi and different can numbers. For example, the sterilization temperature of canned mushroom is 113,121 ℃ and the time is 15min, while the sterilization time of canned straw mushroom is 130℃.

(10) cooling. Sterilized cans should be immediately put into cold water to cool quickly, and the temperature should drop as quickly as possible.

(11) print the package. Cans that pass the inspection should be marked on the lid and packed for storage.