(1) Dehumidification Freshly harvested or purchased fresh shiitake mushrooms have a water content of 85% to 95%, which is inconsistent with the requirements of cryogenic storage, transportation, and export. Therefore, it is necessary to carry out dehumidification treatment, that is, to exclude excessive water content of mushrooms. The appropriate moisture content for fresh mushroom exports differs depending on the type of packaging and the time of refrigerating. Generally used as a small package of water content controlled at 80% to 90%; used as a large package of water content controlled at 70% to 80%. The dehumidification method includes drying and dehumidifying, hot air drying and dehumidifying machine dehumidification.
(2) Selecting ticks and slicing The fresh mushrooms that have been cooled must be culled and graded according to the size of the mushrooms, so that the commodity specifications for sale are the same, and they are easy to pack, store, and sell. At the same time, according to a certain product specification grading packaging, can be clearly marked price, reflecting the high price premium.
The grading standards are generally divided into large (L), medium (M), and small (S) grades according to the size of the caps; they are divided into special grades (A) and (B) according to the degree of openness and appearance. There are also more detailed points, such as the size of the cap is divided into four grades of 3,4,6,8 cm.
At present, there is no uniform grading standard in China. It is mainly based on the requirements of merchants. It is also generally based on the size of the cap, using three-tier system, that is, the diameter of the cap is greater than 5.5 cm for the large (L) level; cap diameter is between 4.5 to 5.5 cm for the intermediate (M) level; cap diameter Small grade (S) grades between 3.5 and 4.5 cm. In addition to grading according to the size of the cap, there are also grading combined with a single weight.
The mushrooms used for fresh-keeping export require mushrooms to be round and round, and the middle of the mushroom shank should be centered. The mutton mushroom should be thick, the edges should be neatly trimmed, and the color should be dark brown. The diameter of the cap should be 3.5 cm or more. The mushroom body should have low water content, no sticking debris, and no disease. Infested with insects, maintaining the beautiful form of natural growth.
The step of selecting the grading is to select the grading first. From the adoption or acquisition of fresh mushrooms, first remove the shape, size, color, etc. that do not meet the above-mentioned export quality requirements and excessively open umbrellas, and perform other treatments (such as fresh sale or dry production). In accordance with the export requirements of fresh mushrooms, the classification shall be conducted according to the grading standards.
Grading method, the use of hand-selected classification or graded screening with different specifications and graders made of tin plate for mechanical grading, or a combination of the two for grading.
(3) Pre-cooling and cold storage 1 Purpose of pre-cooling and refrigerating of fresh mushrooms Fresh cold preserving and cold storage of mushrooms are important technical links for maintaining freshness and quality of products. If the fresh mushrooms are not pre-cooled, the direct packaging and low-temperature transportation will not only shorten the shelf life, but also consume more cooling energy. Therefore, pre-cooling or short-term refrigeration of fresh mushrooms under certain conditions can reduce the respiration of mushrooms and reduce the consumption of nutrients, inhibit the activity of enzymes, prevent the occurrence of enzymatic browning, and delay the development of various physiological activities. In order to make the fresh mushroom that has been pre-cooled and refrigerated at low temperature have a suitable amount of water content in the low-temperature transportation, better cooling effect can be achieved with less cooling energy and cold insulation measures.
2 Pre-cooling and Refrigeration Methods and Principles The method of pre-cooling and refrigerating mushrooms is the most widely used method of air cooling. The air cooling method can be divided into two kinds: forced ventilation and differential pressure. The latter is most suitable for pre-cooling the mushrooms, but it needs a differential pressure generating device. The forced ventilation method, due to the limited and simple mechanical equipment required for cold storage, as well as being easy to operate and maintain, is currently one of the most popular methods for the export of fresh mushrooms in China.
The air cooling method works on the principle of using the refrigerant to transfer the heat inside the store to the outside of the store during the cycle of the gas-liquid process. When the refrigerant is heat exchanged through the evaporator, the air cooled by the blower immediately after cooling is sent to various places in the store, so that the temperature in the storehouse is lowered, and a constant low temperature in the storehouse is maintained.
3 Main facilities for pre-cooling and cold storage - The cold storage facilities of refrigerators include fixed-type refrigerators and fabricated refrigerators. At present, the main domestic production of mushrooms is more commonly used fixed-living small refrigerators.
Fixed-structure small-scale refrigerators are technical devices that combine the use of mechanical refrigeration with the production of cold machinery and cooling facilities. The constant low temperature required for the refrigerator is ensured by the mechanical refrigeration equipment and the insulated building of the refrigerator. Mechanical refrigeration equipment, usually Freon refrigeration system. Its mechanical devices, except the suspended air cooler installed outside the library, other equipment are installed in the machine room outside the library. Refrigerated capacity is generally several tons to several tens of tons.
4 Use and management of fixed-type small refrigerators Pre-cooling and storage Pre-cooling is carried out in a refrigerator. Pour the dehydrated fresh mushrooms into plastic baskets, store them in a certain way after storage, and avoid stacking. When stacking, the cargo tank should be more than 30cm from the wall. There should be appropriate gaps between the container and the container between the bowl and the bowl in order to facilitate the air circulation, cooling and maintain the temperature distribution within the warehouse. There should be a space of 80 cm between the dome and the ceiling or the cold air outlet to prevent freezing of fresh mushrooms due to being too close to the cold air outlet. The temperature in the storage chamber is maintained at 1 to 4°C, and the pre-cooling final temperature must be above 0°C to prevent freezing or physiological injury. Pre-cooling should be promptly packaged. After packaging or transport at low temperature, or continue to carry out temporary cryogenic storage. However, they cannot be stored and transported at room temperature to prevent deterioration. Packaged pieces that are briefly refrigerated should be stored with unpackaged basket storage.
Temperature Management According to Yan Shao and Fu Fu (995), different storage temperatures have a great influence on the freshness of shiitake mushrooms. When temperature changes or low temperatures are interrupted and the temperature fluctuates to 20°C, the effect on freshness will also be affected. T 诘 诘 诘 轮 轮 诘 诘 诘 诘 诘 诘 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 驮 驮 驮 驮 诶洳乇 诶洳乇 诶洳乇> The lower the storage temperature, the longer the preservation period. However, it is not as low as possible. Generally, it is appropriate to use a minimum temperature that does not cause freezing damage. In practice, the temperature of refrigerated and preserved mushrooms should be controlled at 0 to 1°C, but should not fall below 0°C to prevent freezing injury or irreversible physiological injury.
Humidity management The relative humidity of air trapped in cold storage is often due to the high moisture content of fresh mushrooms at the time of storage, or frequent ingress and egress of goods, and the influx of hot air from the outside into the warehouse. This causes the relative humidity in the warehouse to be too high. , Cold storage is unfavorable. Therefore, in the process of dehumidification of fresh mushrooms, it is necessary to grasp the proper moisture content of the fresh mushrooms; when entering and leaving the cold storage, close the storage doors in time, and try to avoid too many times of goods entering and leaving. The relative humidity of the air in the warehouse is generally controlled to be about 75%. If the humidity is too high, dehumidifiers can also be dehumidified if necessary.
Fresh mushrooms that have been ventilated and ventilated in refrigerators are still undergoing faint respiration. The metabolic processes of various substances have not been suspended. The gases such as carbon dioxide, ethylene, ethanol, and acetaldehyde released, if accumulated to a certain extent, It will lead to physiological disorders and deterioration of quality of fresh mushrooms. Therefore, pay attention to ventilation. It is usually chosen to take place at a lower temperature during the day. At the same time, it is necessary to combine the use of refrigeration machinery to slow down changes in the temperature and humidity inside the warehouse.
(4) scientific packaging scientific packaging technology, including the use of appropriate packaging materials and the use of appropriate packaging. It is combined with cryogenic refrigeration and transportation. It is the most commonly used mushroom preservation technology at home and abroad. Scientific packaging can make use of the respiration of fresh mushrooms and reduce the oxygen concentration in the sealed packaging container, increase the concentration of carbon dioxide, and then refrigerated and transported under low temperature conditions to create a good ecological condition for preservation - low temperature , low oxygen and high carbon dioxide, which can achieve the following effects of preservation; First, inhibit the activity of enzymes and microbial activities to prevent enzymatic browning brown spoilage; second is to reduce the respiratory intensity of the mushroom brown transpiration intensity, reduce nutrition Material consumption Brown water loss to prevent loss of freshness and weight loss; Third, delay the process of various physiological and biochemical, inhibit opening, open umbrellas, extend the preservation period.
After the scientific packaging of fresh mushrooms, in addition to achieving the main purpose of keeping brown quality, it can also make the products beautiful and generous, facilitate the discharge on the shelves, and improve the competitiveness of the products. Scientific packaging technology, the main points are as follows:
1 Packaging materials and packaging materials for mechanical preservation of shiitake mushrooms are mainly plastic products. In addition to ordinary plastic vacuum packaging and net bag packaging, most of the tray type stretch film packaging. The size of the tray varies with the amount of packaging, 15 cm X 11 cm X 2.5 cm (100 g), 15 cm X 11 cm X 3 cm (200 g), and 15 cm X 11 cm X 4 cm (300 g) Species. Tensile plastic wrap is 300 mm wide. The length of each tube is less than 500 meters, and the thickness is 10-15 micrometers. The raw materials used for trays and cling film in Japan are:
Low-density polyethylene (symbol LDPE) has the best waterproof and air permeability, and can be used as a variety of anti-fogging cling film and trays.
Polypropylene (PP) An extremely thin film can be made from heat-set biaxially oriented polypropylene (OPP) material.
(2) Selecting ticks and slicing The fresh mushrooms that have been cooled must be culled and graded according to the size of the mushrooms, so that the commodity specifications for sale are the same, and they are easy to pack, store, and sell. At the same time, according to a certain product specification grading packaging, can be clearly marked price, reflecting the high price premium.
The grading standards are generally divided into large (L), medium (M), and small (S) grades according to the size of the caps; they are divided into special grades (A) and (B) according to the degree of openness and appearance. There are also more detailed points, such as the size of the cap is divided into four grades of 3,4,6,8 cm.
At present, there is no uniform grading standard in China. It is mainly based on the requirements of merchants. It is also generally based on the size of the cap, using three-tier system, that is, the diameter of the cap is greater than 5.5 cm for the large (L) level; cap diameter is between 4.5 to 5.5 cm for the intermediate (M) level; cap diameter Small grade (S) grades between 3.5 and 4.5 cm. In addition to grading according to the size of the cap, there are also grading combined with a single weight.
The mushrooms used for fresh-keeping export require mushrooms to be round and round, and the middle of the mushroom shank should be centered. The mutton mushroom should be thick, the edges should be neatly trimmed, and the color should be dark brown. The diameter of the cap should be 3.5 cm or more. The mushroom body should have low water content, no sticking debris, and no disease. Infested with insects, maintaining the beautiful form of natural growth.
The step of selecting the grading is to select the grading first. From the adoption or acquisition of fresh mushrooms, first remove the shape, size, color, etc. that do not meet the above-mentioned export quality requirements and excessively open umbrellas, and perform other treatments (such as fresh sale or dry production). In accordance with the export requirements of fresh mushrooms, the classification shall be conducted according to the grading standards.
Grading method, the use of hand-selected classification or graded screening with different specifications and graders made of tin plate for mechanical grading, or a combination of the two for grading.
(3) Pre-cooling and cold storage 1 Purpose of pre-cooling and refrigerating of fresh mushrooms Fresh cold preserving and cold storage of mushrooms are important technical links for maintaining freshness and quality of products. If the fresh mushrooms are not pre-cooled, the direct packaging and low-temperature transportation will not only shorten the shelf life, but also consume more cooling energy. Therefore, pre-cooling or short-term refrigeration of fresh mushrooms under certain conditions can reduce the respiration of mushrooms and reduce the consumption of nutrients, inhibit the activity of enzymes, prevent the occurrence of enzymatic browning, and delay the development of various physiological activities. In order to make the fresh mushroom that has been pre-cooled and refrigerated at low temperature have a suitable amount of water content in the low-temperature transportation, better cooling effect can be achieved with less cooling energy and cold insulation measures.
2 Pre-cooling and Refrigeration Methods and Principles The method of pre-cooling and refrigerating mushrooms is the most widely used method of air cooling. The air cooling method can be divided into two kinds: forced ventilation and differential pressure. The latter is most suitable for pre-cooling the mushrooms, but it needs a differential pressure generating device. The forced ventilation method, due to the limited and simple mechanical equipment required for cold storage, as well as being easy to operate and maintain, is currently one of the most popular methods for the export of fresh mushrooms in China.
The air cooling method works on the principle of using the refrigerant to transfer the heat inside the store to the outside of the store during the cycle of the gas-liquid process. When the refrigerant is heat exchanged through the evaporator, the air cooled by the blower immediately after cooling is sent to various places in the store, so that the temperature in the storehouse is lowered, and a constant low temperature in the storehouse is maintained.
3 Main facilities for pre-cooling and cold storage - The cold storage facilities of refrigerators include fixed-type refrigerators and fabricated refrigerators. At present, the main domestic production of mushrooms is more commonly used fixed-living small refrigerators.
Fixed-structure small-scale refrigerators are technical devices that combine the use of mechanical refrigeration with the production of cold machinery and cooling facilities. The constant low temperature required for the refrigerator is ensured by the mechanical refrigeration equipment and the insulated building of the refrigerator. Mechanical refrigeration equipment, usually Freon refrigeration system. Its mechanical devices, except the suspended air cooler installed outside the library, other equipment are installed in the machine room outside the library. Refrigerated capacity is generally several tons to several tens of tons.
4 Use and management of fixed-type small refrigerators Pre-cooling and storage Pre-cooling is carried out in a refrigerator. Pour the dehydrated fresh mushrooms into plastic baskets, store them in a certain way after storage, and avoid stacking. When stacking, the cargo tank should be more than 30cm from the wall. There should be appropriate gaps between the container and the container between the bowl and the bowl in order to facilitate the air circulation, cooling and maintain the temperature distribution within the warehouse. There should be a space of 80 cm between the dome and the ceiling or the cold air outlet to prevent freezing of fresh mushrooms due to being too close to the cold air outlet. The temperature in the storage chamber is maintained at 1 to 4°C, and the pre-cooling final temperature must be above 0°C to prevent freezing or physiological injury. Pre-cooling should be promptly packaged. After packaging or transport at low temperature, or continue to carry out temporary cryogenic storage. However, they cannot be stored and transported at room temperature to prevent deterioration. Packaged pieces that are briefly refrigerated should be stored with unpackaged basket storage.
Temperature Management According to Yan Shao and Fu Fu (995), different storage temperatures have a great influence on the freshness of shiitake mushrooms. When temperature changes or low temperatures are interrupted and the temperature fluctuates to 20°C, the effect on freshness will also be affected. T 诘 诘 诘 轮 轮 诘 诘 诘 诘 诘 诘 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 识 驮 驮 驮 驮 诶洳乇 诶洳乇 诶洳乇> The lower the storage temperature, the longer the preservation period. However, it is not as low as possible. Generally, it is appropriate to use a minimum temperature that does not cause freezing damage. In practice, the temperature of refrigerated and preserved mushrooms should be controlled at 0 to 1°C, but should not fall below 0°C to prevent freezing injury or irreversible physiological injury.
Humidity management The relative humidity of air trapped in cold storage is often due to the high moisture content of fresh mushrooms at the time of storage, or frequent ingress and egress of goods, and the influx of hot air from the outside into the warehouse. This causes the relative humidity in the warehouse to be too high. , Cold storage is unfavorable. Therefore, in the process of dehumidification of fresh mushrooms, it is necessary to grasp the proper moisture content of the fresh mushrooms; when entering and leaving the cold storage, close the storage doors in time, and try to avoid too many times of goods entering and leaving. The relative humidity of the air in the warehouse is generally controlled to be about 75%. If the humidity is too high, dehumidifiers can also be dehumidified if necessary.
Fresh mushrooms that have been ventilated and ventilated in refrigerators are still undergoing faint respiration. The metabolic processes of various substances have not been suspended. The gases such as carbon dioxide, ethylene, ethanol, and acetaldehyde released, if accumulated to a certain extent, It will lead to physiological disorders and deterioration of quality of fresh mushrooms. Therefore, pay attention to ventilation. It is usually chosen to take place at a lower temperature during the day. At the same time, it is necessary to combine the use of refrigeration machinery to slow down changes in the temperature and humidity inside the warehouse.
(4) scientific packaging scientific packaging technology, including the use of appropriate packaging materials and the use of appropriate packaging. It is combined with cryogenic refrigeration and transportation. It is the most commonly used mushroom preservation technology at home and abroad. Scientific packaging can make use of the respiration of fresh mushrooms and reduce the oxygen concentration in the sealed packaging container, increase the concentration of carbon dioxide, and then refrigerated and transported under low temperature conditions to create a good ecological condition for preservation - low temperature , low oxygen and high carbon dioxide, which can achieve the following effects of preservation; First, inhibit the activity of enzymes and microbial activities to prevent enzymatic browning brown spoilage; second is to reduce the respiratory intensity of the mushroom brown transpiration intensity, reduce nutrition Material consumption Brown water loss to prevent loss of freshness and weight loss; Third, delay the process of various physiological and biochemical, inhibit opening, open umbrellas, extend the preservation period.
After the scientific packaging of fresh mushrooms, in addition to achieving the main purpose of keeping brown quality, it can also make the products beautiful and generous, facilitate the discharge on the shelves, and improve the competitiveness of the products. Scientific packaging technology, the main points are as follows:
1 Packaging materials and packaging materials for mechanical preservation of shiitake mushrooms are mainly plastic products. In addition to ordinary plastic vacuum packaging and net bag packaging, most of the tray type stretch film packaging. The size of the tray varies with the amount of packaging, 15 cm X 11 cm X 2.5 cm (100 g), 15 cm X 11 cm X 3 cm (200 g), and 15 cm X 11 cm X 4 cm (300 g) Species. Tensile plastic wrap is 300 mm wide. The length of each tube is less than 500 meters, and the thickness is 10-15 micrometers. The raw materials used for trays and cling film in Japan are:
Low-density polyethylene (symbol LDPE) has the best waterproof and air permeability, and can be used as a variety of anti-fogging cling film and trays.
Polypropylene (PP) An extremely thin film can be made from heat-set biaxially oriented polypropylene (OPP) material.
3L-size Carrot,3L-size Red Color Carrot,Big Size Carrot,3L-size Premium Carrots
Yirun Agricultural Cooperative , https://www.yiruncn.com