Drying and candied fruit processing techniques of edible fungi to explore the high-yield cultivation techniques of edible fungi.

Core hint: edible fungi are edible mushrooms; mushrooms refer to higher fungi that can form large fleshy (or glial) fruiting bodies or sclerotia tissues.

Edible fungi are edible mushrooms; mushrooms refer to higher fungi that can form large fleshy (or glial) fruiting bodies or sclerotia tissues. At present, more than 120000 species of fungi have been described in the world, of which more than 6000 species can form large fruiting bodies or sclerotia, and more than 2000 species are edible.

China is rich in edible fungi resources, and it is also one of the earliest countries to cultivate and utilize edible fungi. The protein content of mushrooms is generally 1.5% of fresh mushrooms and 15% of dried mushrooms, which is higher than that of ordinary vegetables, and its amino acid composition is more comprehensive. Most mushrooms contain eight essential amino acids. Among them, mushroom, straw mushroom, Flammulina velutipes are rich in lysine, while lack of grain, lysine is conducive to the physical and intellectual development of children. Mushrooms contain a variety of vitamins and a variety of physiologically active mineral elements. Such as VB1, VB12, Vc, Vk, VD and phosphorus, sodium, potassium, calcium, iron and many trace elements, can supplement the deficiencies in other foods [4].

Edible mushroom is not only delicious, but also nutritious, which is often called health food. It not only contains all kinds of essential amino acids, but also can reduce blood cholesterol and treat hypertension. In recent years, it has also been found that Lentinus edodes, mushrooms, Flammulina velutipes and hericium Erinaceus contain substances that enhance the anti-cancer ability of the human body.

Edible fungi contain bioactive substances such as macromolecular polysaccharides, β-glucose and RNA complex, natural organic germanium, nucleic acid degradation products, cAMP and triterpenes, which have important utilization value for the maintenance of human health.

In recent years, a large number of health foods, health drinks, wine and drugs produced and processed from edible fungi have been widely used in medical clinic and put into the market of health products. Therefore, as a kind of green food, edible fungus has been paid more and more attention by people all over the world.

1. Dried edible fungus

Edible fungi have high water content, fresh and tender bacteria and strong post-ripening. Perishable, mass production or large-scale cultivation, the quality of drying processing will be directly related to the economic benefits of producers. The drying methods of edible fungi can be divided into two types: natural drying and artificial drying. In the drying process, the speed of drying has a decisive impact on the quality of dried products. The faster the drying speed, the better the product quality.

At present, a large number of equipment are widely used in our country, such as linear rising temperature drying room, same fire rising temperature drying room, hot air dehydration dryer, steam dehydration dryer, infrared dehydration dryer and so on. There are a variety of dehydration and drying processes for edible mushrooms. Taking Lentinus edodes as an example, in order to make the mushroom shape round, the cover crimped thick, the mushroom pleated bright yellow, rich flavor, and water content up to 12% of the export standard, we must grasp the following links: 1. Strict picking; 2. Timely drying; 3. Finishing, installation and baking; 4. Master the heat. Low temperature drying; 5. Pay attention to dehumidification and ventilation.

1.1 drying technology

Drying processing of edible fungi. There are two methods: natural drying and mechanical drying.

1.1.1 Natural drying

Using sunlight as heat source and natural wind as auxiliary drying, it is suitable for bamboo shoot, Tremella fuciformis, fungus, Flammulina velutipes, Ganoderma lucidum and other varieties. This method is simple, ancient and less investment. When processing, the bacteria do not squeeze each other on the bamboo curtain to dry, turn over the sun to light, to prevent damage, generally 2-3 days to dry. This method is suitable for small-scale processing plants. In order to save money, some processing plants bake selenium until it is semi-dry, but it needs to be flexibly mastered according to the weather and water content of bacteria to prevent mushroom deformation, discoloration and even decay.

1.1.2 Mechanical drying

Use ovens, cages and baking rooms. Or carbon hot air, electric heating and infrared and other heat sources to make bacteria dehydration and drying methods, at present, a large number of uses are linear rising temperature drying room, tempering drying room and hot air dehydration dryer, steam dehydration dryer, infrared dehydration dryer and so on.

1.2 factors affecting drying

1.2.1 temperature of drying medium

Mushroom drying is to use preheated air as the drying medium, but it is not dry, it is a mixture of air and water vapor. To make the mushroom (ear) body dry continuously, the temperature of air and water vapor must be continuously increased. In this way, the moisture of mushroom (ear) body can evaporate easily. the drying rate is accelerated. When the relative humidity in the air decreases, the lO% saturation difference increases by 100%, so we can increase the temperature and decrease the relative humidity to improve the drying quality.

When the edible fungus is dried. Especially in the initial stage, it is generally not suitable to use too high temperature, otherwise it is due to sudden high temperature. The rapid expansion of juice in the tissue is easy to break the cell wall and lose the internal solubility. sugar and other organic compounds in raw materials are often decomposed or coked at high temperature, damaging the appearance and flavor of the products. early high temperature and low humidity are easy to cause crusts and affect water diffusion [2].

1.2.2 humidity of drying medium

The air temperature rises. The relative humidity decreases. Under the condition of constant temperature. the lower the relative humidity, the greater the air saturation difference, and the faster the drying speed of edible fungi. If the temperature increases and the relative humidity decreases at the same time, the greater the difference between the raw material and the external water vapor, the easier the evaporation of water will be.

1.2.3 Speed of airflow circulation

The faster the flow speed of dry air, the faster the evaporation of water on the surface of edible fungi. Increasing the air flow speed has two functions: one is to quickly transfer the heat of the air to the raw material to maintain its evaporation temperature; the other is to quickly take away the evaporated water from the raw material and constantly replenish the fresh unsaturated narrow gas. Promote the continuous evaporation of water on the surface of raw materials. According to the measurement. When the wind speed is below 3m/s, the water evaporation rate is directly proportional to the wind speed [2].

1.2.4 species and status of edible fungi

The kinds of edible fungi are different. the chemical composition and tissue structure are also different, so the speed of drying is also different. The size of raw material cut is directly related to the drying speed. The slicing is small and the evaporation area is large. The faster it dries.

1.2.5 loading capacity of raw materials

The number and thickness of loaded mushrooms are based on the principle of not interfering with air circulation. The quantity and thickness of loaded raw materials have an effect on the drying rate of raw materials. The raw materials on the baking pan are loaded with peta. if the thickness is large, it is not conducive to air circulation. Affect water evaporation. The thickness of the raw material can be changed with the change of the volume of the raw material in the drying process. It is easy to be thinner at the beginning of drying and thicker at the later stage of drying.

two。 Processing of candied mushrooms

Edible mushroom candied fruit is a kind of edible mushroom refined product cooked with thick syrup, which is a kind of leisure food with unique flavor and rich nutrition, and can be used as an auxiliary material for the production of pastry, Eight Delicacies Rice and convenient soup. Edible mushrooms suitable for making candied fruits are mushrooms, Pleurotus ostreatus, Flammulina velutipes, hericium Erinaceus, Tremella fuciformis, small fungus and so on. It requires fresh raw materials, delicate texture and low fiber content. For the products with moist surface, no sugar juice and 30% water content, it is generally called edible mushroom candied fruit; the surface is relatively dry, there is no sugar juice and the water content is low. It is called preserved edible mushroom [3].

2.1 production technology of preserved Pleurotus ostreatus

Material selection: the young fruiting body of the mushroom body is finished, the meat is thick, and the young fruit body which is basically unopened is used as the raw material. Because of the difference in texture between Pleurotus ostreatus seedling cover and stalk tissue, the porch processed the two separately. The mushroom cap should be intact and generally not trimmed; the stalk can be cut into 2~3cm, thick l.00~1.15cm mushroom strips, rinsed and drained for use, processed with dried mushroom stalks, soaked in clean water for 4 hours, softened and then rinsed.

Blanching: the bacterial cap should be blanched twice. The water temperature of the first blanching was 9500min, the blanching time was 25min, the second blanching temperature was 8085℃, the blanching 5~7min was 5~7min, the fungal stalk was blanched once, the water temperature was 9500min, the blanching 7~8min was 7~8min. After picking it up, quickly put in a cold water towel to cool.

Hardening treatment: soak in 0.4% 0.5% calcium chloride aqueous solution, the mass ratio of Pleurotus ostreatus to water is 2, the treatment time is 8 hours, and then wash off the residue with clean water. The second blanching of the cap was carried out at this time. Can also use 5% of the mass fraction of lime water as hardener, treatment, the cap cooking time is 60min, the sugar solution can be concentrated to 72%, the pot can be started. When boiling sugar, the color of the mushroom will change (gray-white gray-light yellow-yellow-residual yellow).

Drying (icing), packaging: the semi-finished product is transferred to the drying room and dried at 50 ~ 55 °C. the temperature should not exceed 65 °C, and the drying time is about 4 hours. it is often turned over during the period, and can be packed after cooling. If the candied fruit is processed with the mushroom stalk, you can wrap the refined clothes after drying, that is, add the white essence to the human water, boil until shredded, and then pour the dried mushroom stalk into the pan to stir, wrap it on the surface of the mushroom body and form a white fine coat. Then rinse with clean water for 48 hours, change the water 5 times for 6 times, cold soak the sugar: drain the rinsed mushroom and put it into the sugar solution with a mass fraction of 40%. Soak for 5 hours for 6 hours, so that the mushroom body initially precipitate water, in order to reduce the damage when boiling sugar.

Boil sugar: start with syrup. The mass fraction of syrup is 70% 80%, citric acid 0.8% 10%. Sodium benzoate 0.05%, successively put into water, boil, put people in cold-soaked Pleurotus ostreatus, boil over high heat, and then use a gentle fire to keep the sugar liquid slightly boiling. When cooking, the evaporated water should be replenished at any time to prevent scorching, so that the sugar seedling content should be kept above 55%, and then packaged. Candied fruit packaging is generally divided into two layers, first wrapped in cellophane, the mushroom size of 1 / package. Small 2 to 3 / package, and then slowly into a plastic bag to seal. The preserved products of Pleurotus ostreatus basically keep the fan-shaped structure of fresh mushrooms, golden amber color, strong transparency and good taste, and can be preserved for 1 year at room temperature [3].

2.2 Straw mushroom candied fruit

Material selection treatment: select straw mushroom with full body, no umbrella and no mechanical damage. immediately after harvest, it was treated in 0.03% sodium pyrosulfite solution for 8 hours, and then rinsed with clean water.

Bleaching and hardening: blanch the treated straw mushroom in brushed water for 2 minutes. To kill the enzyme activity. Remove immediately after blanching. Cool in cold water. Cool and fish out. Soak in 0.5%-1% calcium chloride solution for 1-2 hours. After hardening, rinse with clean water 34 times to remove the residual liquid. Then remove and drain. Keep in 85 ℃ hot water for 5 minutes. Rinse in clean water for 34 times.

Cold sugar solution: put the rinsed volvariella volvacea in 40% sugar solution for 12 hours.

Concentration: add white sugar after cooling, so that the concentration of sugar solution reaches 60%. Pour straw mushrooms and sugar solution into a stainless steel pot or aluminum pot. Bring to a boil over high fire, then use a gentle fire. Boil until the temperature of the sugar solution reaches 108 min 110 °C, start the pot when the sugar concentration is about 75% (determined by a sugar meter).

Baking sugar table: the temperature of the drying room should not exceed 60 °C. Bake for about 4 hours and turn frequently until the surface of volvariella volvacea does not dry up. Then coat with white sugar powder (dry and grind the white sugar at 60-70 ℃). The dosage is lO% of straw mushroom. Stir well and sift out the excess powdered sugar. Then pack it according to the predetermined specification [4].

2.3 candied hericium Erinaceus

Material selection and treatment: fresh monkey head mushrooms with normal shape, white or yellowish color, no mildew and no scar injury were selected as raw materials. Cut off the root. Remove the debris and impurities attached to the thorn. Soak it in 2% salt water immediately and process it as soon as possible.

Scalding: put fresh water in the pot. Add the right amount of citric acid. Boil the hericium Erinaceus for 5 minutes and remove. Wash quickly with cold water. The larger individuals should be properly segmented. Make the mushroom body uniform and remove the seriously damaged mushroom body.

Solution immersion: prepare a solution containing sodium pyrosulfite O. 2%. And add the right amount of calcium chloride. Put into the mushroom body after melting. Soak for 6-8 hours. Pick it up and rinse with clean water.

Pickling: according to the weight of the mushroom. add people and% sugar to marinate. 24 hours later. Filter the sugar solution and heat it to the boil. and adjust the concentration of the pond liquid to 50. Pour it into the tank while it is hot. the sugar solution flooded the mushroom body and continued to marinate for 24 hours.

Heat and concentrate: pour the mushroom body together with the sugar solution into the pot. Heat and boil. Gradually add sugar and an appropriate amount of converted sugar solution. Boil the mushroom body until it has a sense of transparency. When the sugar concentration reaches more than 60%. Pour the sugar solution with the mushroom body into the impregnation tank, pick up and drain the sugar solution after soaking.

Baking: put the mushroom body on a plate and flatten out. Into the baking room. Bake at 60-65 ℃ for 8-10 hours. When the moisture content of the mushroom body is reduced to 24%-26%. Take out the baking pan. Reshape the mushroom after 16-24 hours of moisture regaining. Press the mushroom into flat sliced mushrooms. Then send it to the baking room for a second baking. The temperature is controlled at 55 ℃. Bake for about 6-8 hours. The water content is reduced to 17%. When you can't touch it with your hands, you can get out of the drying room. after moisture recovery treatment, it can be packed [8].