Pear is known in China as the "grand fact of a hundred fruits." It is one of the fruits of long history, large area and high yield in China. Therefore, China is recognized as the hometown of pears by the world. Because pears are crisp, juicy, sweet and sour, and aromatic, they are very popular with consumers. However, the quality of stored pears has a direct relationship with its economic benefits, and the main factors affecting the pear's tolerance to Tibet are variety characteristics, maturity, cultivation conditions, pest control and other aspects. In addition, management techniques during storage, cooling rate at the initial stage of storage, humidity adjustment in the library, ventilation, etc., will also affect the period of resistance to pome fruit. 1. Harvest time (1) Appropriate harvest time at appropriate time can be determined according to the characteristics of the species and the length of the storage period. For the pear and sand pear system varieties, when the fruit surface shows the inherent color of the species, the meat becomes hard and brittle, the seed color becomes brown, and fruit stems can be harvested easily when they fall off from the fruit platform. For varieties of Pear and Qiutian pear systems, because they have obvious after-ripening changes, they can be harvested as early as possible. That is, the size of the fruit has been basically set, the fruit surface has begun to decline, the seeds have not yet browned, and fruit stems have fallen off easily from the fruit stage. Harvesting is good. (2) Harmless harvesting requirements Avoid damages such as rubbing, bumping, pressing, stabbing, smashing, etc. in picking, loading baskets (cartons), loading and unloading vehicles, and transportation, and reduce the number of baskets (cases) and replacements. The loading and yards should be filled and tightly packed to avoid extrusion, friction, and puncture injuries caused by transport jolts, so as to reduce deterioration and deterioration during storage. 2. Pre-storage treatment (1) Preharvest pome fruits are still undergoing vigorous respiration, evaporation, decomposition and depletion after they are harvested. At the same time, the pear fruit will release a large amount of field heat after harvesting from the field, which will cause post-harvest The temperature around the pear fruit rapidly rises, accelerating mature aging, and its freshness and quality are significantly reduced. Therefore, in the short period of time after the pear fruit is harvested, it must be cooled to 3°C to 4°C in the raw material production area so that the pear fruit can maintain a low level of life so as to delay aging. Pear fruit pre-cooling methods include air pre-cooling, cold water pre-cooling, vacuum pre-cooling and wet pre-cooling. (2) Cleaning and grading Pear fruits are washed with clean water to remove the pests and microorganisms on the surface, then the pests and fruits are removed, and the pear fruits are graded according to the requirements of the grade. (3) The coating film is a measure taken to make pear fruit more resistant to storage. 1 Rouge coating agent. Its main component is glyceride in water-insoluble fatty Acids. Its raw material ratio is: 400g soybean oil, 2.5g aliphatic monoglyceride, 2g casein sodium, 1g agar, 1000mL of water, deployment and usage methods: The agar was soaked in warm water and heated until it swelled. Aliphatic monoglyceride, casein sodium, and soybean oil were then added, and the emulsion was obtained by high-speed stirring. The freshness of the preservative is natural and does not contain toxic substances. The pear fruit is soaked in the emulsion, and dried after being taken out, which can significantly prolong the preservation period. 2 Wax coating agent. The ratio of raw materials is: 100g of beeswax, 20g of casein sodium, and 10g of sucrose fatty Acid esters. The total use is as follows: dissolve beeswax and sucrose fatty acid esters in ethanol, and dissolve casein sodium in water. After the solution was mixed, the solution was dissolved to 1000 mL, and the mixture was rapidly stirred and emulsified to be the required preservative. The preservatives are non-toxic, safe to use, and have a suitable consistency. 3 natural resin film coating agent. The alcohol-soluble shellac of natural resin has good film formation, fast drying and luster, and is relatively stable in air, and is suitable for use as a film preservative. Its raw material ratio is: shellac 50g, sodium hydroxide 20g, ethanol 80mL, ethylene glycol 8mL, water 1500mL, deployment and use methods: the shellac is added to the porcelain containing ethanol, ethylene glycol mixture soaked , Dissolve, add an aqueous solution of sodium hydroxide, and heat and stir to saponify the dissolved shellac. The pear fruit is soaked in the solution, taken out and air-dried to form a thin layer of transparent plastic wrap. (4) The packaging pear fruit generally does not use the thin film single fruit packaging or the carton liner film packaging method, because it will make the volume fraction of carbon dioxide is too high and easy to cause flesh, brown heart. If it is packaged in 0.01mm to O.02mm thick polyethylene sachets, it will not only have a significant effect on preservation, but also will not cause carbon dioxide damage to pear fruit. It is a simple, economical and practical treatment. In addition, the pear fruit can be packaged in paper and foam nets, placed in a carton, and punched in the carton side to achieve ventilation and preservation. 3. Storage and preservation Store, clean, disinfect, and wash (with 1% to 2% bleaching liquid) before storing, and then use sulphur powder (5g/m3 to 15g/m3) or warehouse disinfectant (5g/m) before storage. Cubic meters) Multi-point ignition, closed fumigation 12h ~ 24h, then open the door fully ventilated 1 day ~ 2 days. (1) The cellar is used in the cellar of pear fruit. After a series of treatments, the harvested pears can enter the pit when the temperature and cellar temperature are close to 0°C. When entering the pit, different grades of pears are piled up separately and generally no longer selected. When pears are palletized in the kiln, care should be taken to keep ventilation clearances around the chambers, boxes, and squats. In the early stage of product storage, the main management work is to control the ventilation, import the cold air outside the library, eliminate the hot air in the warehouse, lower the temperature in the warehouse, and prompt the product to cool down as soon as possible. If necessary, the library door can be opened to increase the air flow. In the medium term, frost protection is the mainstay. During this period of management, special attention should be paid to cold protection. When the ventilation system is turned off, the air in the storage tank is properly replaced. However, the air outlet can only be opened during the daytime or outside of the library when the air temperature is higher than the freezing temperature. Proper ventilation. When the spring comes, the temperature outside the reservoir and the soil temperature gradually rise. If it is difficult to maintain the low temperature conditions in the reservoir, the inlet and outlet ports are opened again. Cold air is introduced to adjust the temperature inside the reservoir. When the outside air temperature is lower than the temperature inside the reservoir, ventilation is performed. When the outside temperature rises further and the night temperature is difficult to adjust to a suitable low temperature, the product should be promptly sold to the library. (2) Ventilation storeroom storage The storage of the pears is a kind of storage method that uses natural low temperature in winter, large temperature difference between day and night, and ventilation and insulation properties to keep the pears under relatively stable lower temperature conditions and delay decay. The practice is: after the pear fruit is harvested, the basket is put into storage, and the stacking code is ventilated. According to the temperature difference between the inside and outside of the library, the windows are opened or the window is closed flexibly, and the temperature and humidity inside the warehouse are adjusted so that the temperature is maintained at -3°C to 1°C. Relative humidity is between 85% and 93%. Cold season should pay attention to antifreeze, especially for varieties that are sensitive to low temperatures. (3) cold storage should pay attention to the occurrence of chilling injury during storage in cold storage. Pear fruits that have been pre-cooled to 0°C can be directly stored in cold storage; pear fruits that have not been precooled can not be directly refrigerated into cold storage, otherwise black heart disease can occur. serious. Generally, storage is performed at a temperature above 10°C, 1°C per week, and after decreasing to 7°C to 8°C, the temperature is lowered by 1°C every 3 days until it reaches 0°C. This period takes about 30 days to 50 days. In the cold storage, there are two types of cartons, product type and honeycomb type. The carton code must not be too large. There should be a void in the carton between the carton. A ventilation channel should be left between the carp and the carp. The direction of the ventilation channel should be perpendicular to the direction of the fan or parallel to the direction of the wind direction. (4) Compared with ordinary cold storage, the storage period is prolonged by 1 time compared with ordinary cold storage, and the shelf life of fruits and vegetables after delivery can be extended to 21 days to 28 days, which is 3 times to 4 times that of ordinary cold storage, keeping fruits and vegetables fresh. Degree of brittleness, nutrient composition and hardness, color, quality, etc. are almost the same as the new picking state, with excellent storage effect. The controlled storage of pears can be stored in a controlled-air mode consisting of oxygen with a volume fraction of 12% to 13% and carbon dioxide of 1% or less, but it is necessary to prevent the browning of the flesh and fruit core due to the accumulation of carbon dioxide. (5) Decompression storage This is a combination of cooling and low pressure storage. The method is to use a vacuum pump to extract air in the cold room where pome fruits are stored, so that the indoor pressure is reduced to a certain degree, and the pressure is kept low throughout the storage period. Through the pressure regulator, fresh air is continuously passed into the cold room through the humidifier, so that the pear fruit in the room is always in a constant low pressure, low temperature, high humidity and fresh air storage environment. Its storage and preservation period is 1 to 2 times longer than ordinary cold storage. 4. Existing problems and preventive measures (1) Storage in a timely manner Some countries and regions with advanced fruit storage in the world should put fruits in storage within 24 hours as an important measure for the preservation and preservation of fresh fruits. After fruit is harvested, treatment at room temperature can not be stored in time, which is one of the main causes of fruit rot, weightlessness, and quality decline, and it leads to a shortened storage period and induces physiological diseases in the late storage period. To do this well, the storage place should be built around the place of production or the orchard. (2) Dry consumption of pears and humidity in the warehouse The pear fruit has high moisture content and water loss during storage is one of the major problems. In order to reduce water loss, it is necessary to increase the humidity in the storage room. Floors can be sprinkled with water, or wet curtains can be placed around the wall of the warehouse, ventilation ducts, etc. When the cartons are stacked, the plastic sheeting can also be placed on the floor to reduce ventilation. Loss of moisture. (3) Accumulation of carbon dioxide and ventilated air changes Ya pear, snow pear, Ci pear, and long pear in the library when the carbon dioxide volume fraction is higher than 2% will cause fruit, brown flesh and other diseases. Therefore, strengthening the warehouse ventilation, reducing carbon dioxide accumulation, and reducing the accumulation of harmful gases such as ethylene, is the key to the storage of pear fruit technology. Therefore, it is necessary to ventilate every day for 1h to 2h in the early and late stages of storage, and every 2 to 3 days in the middle stage for 1h to 2h. (4) Preservation measures in the transportation process Preservation measures in the transportation process are also a very important link. The transportation and preservation equipment mainly includes ice refrigerated trucks, mechanical refrigerated trucks, insulated vehicles, refrigerated containers and air transport and preservation. Among them, air transport preservation is a new type of packing box with air-conditioning performance. This packing box has a special layer of film fiber and can Absorb oxygen molecules and allow nitrogen to pass through, so that after the air enters the packing box through the membrane, the nitrogen content in the tank can be as high as 98%, so that the respiration of pears can be slowed down, and the purpose of keeping freshness for a long time can be achieved.
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