Three main links of storage and preservation of fruits and vegetables

The ultimate goal of storage and preservation of fruits and vegetables is to keep fruits and vegetables fresh and have good quality and flavor. Therefore, comprehensive measures are needed, which include measures to increase the pre-harvest storage resistance of fruits and vegetables. The length of the storage period of fruits and vegetables and the quality of preservation are mainly restricted by four links. The first is the pre-harvest factors, including variety, fertilization, irrigation, pest control, pruning, and thinning and thinning of fruit; the second is harvesting, storage, packing and transportation before the storage is received for storage; the third is management during storage, including Temperature, humidity, ventilation; Fourth, out of storage, sales. These four links are bound together. If there is a link that does not work well, it will affect other links. First, the impact of pre-harvest factors on the storage performance of fruits and vegetables Pre-harvest factors, we usually call cultivation practices, is the basis for the preservation of fresh fruits and vegetables. To obtain a good storage effect, the fruits and vegetables that have been placed in the warehouse must have good appearance (the size is suitable, the color of the fruit is correct, no pests and diseases), and the flavor is positive. These are related to the following factors: Variety: The same variety of fruits and vegetables of different varieties, its resistance to Tibetan has a great difference. In general, the longer the growing period, the more resistant to storage, the early varieties are not resistant to storage, the late-maturing varieties are resistant to storage, and the mountainous cultivation is more resistant to storage than the plain, and the quality is good. Apple: Late-maturing varieties are resistant to late-maturing varieties such as Red Star, Marshal, Golden Delicious, Fuji, India, and Guoguang. In recent years, based on consumers' tastes, market sales, and economic benefits, Fuji is the most promising one. The size, color, hardness, and sweetness of the fruit are relatively good and resistant to storage. Should phasing out those varieties with poor flavor and storage. Grapes: Colored varieties are resistant to storage than colorless varieties, and late-maturing varieties are more resistant to storage than early-maturing varieties such as Longan, Jufeng, Rose, American Red and Red Perfumes. Citrus: orange, orange, orange three species, orange, orange is more resistant to storage, such as sweet orange, orange, blood orange, navel orange; citrus such as Jiaogan, Manggan, Guanggan and other resistant storage; oranges Can not be stored for a long time. Pears: Yali pears, snow pears, pears, apple pears, winter pears, jin pears, and red pears are more resistant to storage. Kiwi: Cultivated varieties are more resistant to storage than wild varieties. At present, the cultivars that are more resistant to storage are Haiwat and Qinmei, which can be stored under suitable conditions for more than 6 months. 2. Fertilization: Fertilization has a close relationship with the quality and storage performance of fruits and vegetables, and strives to achieve reasonable fertilization. If nitrogen fertilizer is insufficient, the growth of branches and leaves will be poor and the fruit size will become smaller. Excessive nitrogenous fertilizers showed that the branches and leaves were long, the number of diseases and insects increased, the coloring was poor, and the tolerance to storage was reduced. In the absence of phosphate fertilizer, shoots and fine roots were significantly deficient, and the fruit sugar content decreased and the taste was light. Too much phosphate can cause iron deficiency and zinc deficiency. The application of potash fertilizer is appropriate to promote thick and ripe shoots, improve drought resistance, promote fruit ripening, and improve quality and tolerance. In order to improve the quality of fruits and vegetables and their storage tolerance, organic fertilizers or compound fertilizers should be applied in accordance with the soil fertility and the growth of fruits and vegetables to avoid excessive application of nitrogen fertilizer. And according to the growth of fruits and vegetables in the amount of trace element fertilizers, such as calcium, iron, zinc, manganese fertilizer. 3. Irrigation: Rational irrigation is also very important for improving the storability. For most deciduous fruit trees, if the soil is not very dry before the fruit harvesting period is half a month, water should not be poured to avoid lowering fruit quality or causing cracking. In particular, berries, such as grapes used for storage, should be watered from 7 days to 10 days before harvesting, otherwise the sugar content of the grapes will be reduced and the storage will be affected. 4. Prevention of pests and diseases: As a storage of fruits and vegetables, we must choose healthy fruit without insect eyes and pathogens. II. Harvesting, grading, packaging and transportation of fruits and vegetables. Harvesting, grading, packaging, and transportation of fruits and vegetables are important parts of a good storage of fruits and vegetables. They can directly affect the loss, quality, and storage time of storage and transportation. 1. Harvesting of fruits and vegetables: The harvesting of fruits and vegetables depends on the characteristics of the variety, the maturity of the fruits and vegetables, the length of the storage time, and the weather conditions. The harvest is too early, the fruit is not yet fully developed, small in size, poor in coloration, and low in sugar accumulation. It does not form the inherent flavour and quality of the variety. It is easy to lose water during storage and the skin is easy to shrink. Sometimes it increases the number of physiological diseases. Incidence. Harvested too late, some varieties will be a large number of fruit drop, soft fluffy flesh, high pressure bumps during transportation. At the same time, the fruit is fast-aging and shortens the storage period. Therefore, we must harvest timely. Harvesting period judgment: The harvesting time is determined according to the comprehensive factors such as the fruit size, shape, fruit hardness, fruit color, changes in the fruit's intrinsic chemical substances, and the like. Harvesting technology: The surface structure of the fruit is a good protective layer. Damage and destruction of this protective layer will destroy the storage performance of the fruit, making it susceptible to bacteria and causing decay. Therefore, we must master the correct harvesting techniques and try to avoid mechanical damage. During the harvesting process, strict implementation of the operating procedures is required to ensure that the fruit is intact and prevent breakage of fruit branches. Only by carefully diligently picking, releasing, lightly loading, and unloading, and avoiding nail injuries, crush injuries, stab wounds, and frictional injuries, can the purpose of quality assurance and loss reduction be achieved. 2. Fruit grading: The main purpose of fruit grading is to make it meet certain commodity standards. When grading, the size and color of the fruit are different, susceptible and damaged fruit, according to domestic and foreign trade grading standards for size and quality selection, unqualified as a fruit processing. Grading methods are mainly manual operations, with senses, but there are also the fruit on the conveyor belt to move, and then selected from the classification. 3. Fruit packaging: Fruit packaging is an important measure for standardization, commercialization, and guaranteeing transportation and storage. Packaging is especially important in the transport of modern goods. It not only plays a role in protecting the quality of the fruit, but it is also one of the important factors in reducing costs and expanding sales. With reasonable packaging, it is possible to keep the fruit in good condition during transportation and reach it safely. Reasonable packaging can reduce the mechanical damage caused by mutual friction, collision, and extrusion, reduce the spread of the disease, and avoid the loss caused by fever and severe changes in the temperature of the fruit. 4. Fruit transport: Transport is the link between production, supply, and sales. It is an important link in the circulation of fruits and vegetables. This requires fast loading, fast shipping, quick unloading, and careful handling to reduce mechanical damage. In the transportation process, according to the characteristics of different types of fruits and vegetables, the length of transportation, seasons and weather changes, as far as possible to create a suitable temperature, humidity and other conditions to reduce the loss of fruits and vegetables in transit. At present, many vehicles are equipped with cooling and cold-proof devices, such as refrigerated trucks, railway ice packers, mechanically insulated cars and refrigerated ships. In recent years, containers with temperature-controlled air-conditioning have also been developed to create more suitable conditions for the transportation of fruits and vegetables. Third, the management of storage of fruits and vegetables Storage of fruits and vegetables to determine the method, mainly based on various post-harvest physiological changes in fruits and vegetables, fruits and vegetables, the basic principles of storage, and fruits and vegetables during storage during the different requirements of environmental conditions vary. At present, there are many storage methods used at home and abroad, but they can be summarized into two categories. One is low-temperature storage, that is, the use of natural cooling or artificial cooling (mechanical refrigeration or ice) method to keep the storage environment at a low temperature; the other is to control the gas composition (referred to as controlled atmosphere storage), mostly in the cooling conditions Adjust the gas composition in the storage environment so that it can reach the gas indicators suitable for storage of fruits and vegetables, so as to obtain a better storage effect. 1. The use of natural cold source storage and natural cold storage is one of the low temperature storage methods. It is a method of utilizing and adjusting the natural low temperature to store the storage place at a relatively low temperature, including heaping, sluice, cellar, ventilating storage, and freezing. These storage methods are widely used in China and are still playing a greater role in production. The use of natural cold source storage has the advantages of simple storage structure, low construction cost, etc. However, limited by natural conditions, it can only be applied in low temperature seasons. (1) Heaping: Heaping is a temporary storage method in an orchard or open space. During the accumulation, the fruits are generally stacked directly on the ground or in the shallow ditch (pit) between the rows of fruit trees. According to the temperature changes, the thickening is covered in divided layers to provide shade or cold insulation. The coverings used were made from local materials, such as mats, straw curtains, crop straws, and soil. Coverage time and thickness depend on climate change. Generally, the temperature is high at the early stage of the accumulation. To prevent sun exposure, it is necessary to cover the shade during the day and provide ventilation at night. The autumn wind is relatively large, and after the cover is covered, there is also the effect of heat preservation and rain protection. Afterwards, it gradually decreases with the temperature, and then it is covered by thickening for cold insulation. (2) Gutter: This is also a relatively simple method of fruit storage. Chestnuts, walnuts, hawthorn, etc. use this method more, apples and other fruits also use this method to preserve. As the seasons change, temperature and soil temperature are changing, but the characteristics and laws of change are different. From autumn to winter, the temperature and soil temperature are declining, but the temperature drops rapidly and the soil temperature drops slowly, with a small change. The temperature in winter is very low, while the soil temperature decreases slowly, and the deeper the soil is, the higher the temperature is. By the spring of the following year, the temperature and soil temperature gradually increased, but the temperature rose rapidly and the change was large. The soil temperature rises slowly and changes little. This slow and steady change of soil temperature in winter and spring is beneficial for fruit storage. After the fruit is buried, a relatively high and stable relative humidity can be maintained in the buried ditch, which can prevent fruit wilting and reduce weight loss. After the covered fruits are covered, it is easy to accumulate certain carbon dioxide and form a self-regulating atmosphere, which can reduce the respiration of the fruit and the activity of microorganisms. This can reduce decay loss and prolong storage. (3) Cellar: There are many kinds of storage cellars, among which cellar cellars are the most common. In addition, there are caves in Shanxi, Shaanxi, Henan, and other places, and the storage of citrus in Nanchong, Sichuan, etc., takes the form of a well pit. These cellars are built according to the characteristics of the local natural and geographical conditions. It can use both stable soil temperature and simple ventilation to regulate and control the temperature in the pit. Fruits can be brought into the cellar at any time and can be checked for storage in a timely manner. (4) Air-raid shelters: In order to implement the policy of combining peacetime and warfare, and make full use of the existing civil air defense projects throughout the country, the problem of insufficient space is filled in the storage of fruits. (5) Ventilation storehouse: The ventilator storehouse is the development of the storehouse pit, its form and performance are similar to the pit cellar. The storage management of the ventilation warehouse is mainly in the warehouse with good thermal insulation performance, and a complete and flexible ventilation system is set up. Using the temperature difference between day and night, through the air guide equipment, the low-temperature air outside the library is introduced into the warehouse, and then the interior heat is stored. Bad gases such as air and ethylene are discharged outside the warehouse through the exhaust equipment to maintain a more suitable storage environment for the fruit. However, due to the fact that the ventilation warehouse is cooled and stored by natural temperatures, it is subject to large temperature restrictions, especially in the early and late stages of storage, the warehouse temperature is high, and it is difficult to control, affecting the storage effect. In order to make up for this deficiency, electric fans, blowers, ice, or mechanical refrigeration can be used to accelerate the reduction of the temperature in order to further improve the storage effect and prolong the storage period.

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