Preservation of cold storage is a storage method that inhibits the activity of microorganisms and enzymes and prolongs the longevity of fruits and vegetables. Fresh-keeping cold storage technology is the main method for the preservation of fresh fruits and vegetables at low temperatures. The fresh-keeping temperature of fruits and vegetables ranges from 0°C to 15°C. Fresh-keeping storage can reduce the incidence of pathogenic bacteria and the rot rate of fruits, and can also slow down the process of respiratory metabolism of fruits so as to prevent decay and extend the storage period. Improve the quality of fresh-keeping fruits and vegetables. Fresh-keeping cold storage is a good helper for fresh produce and quality assurance of agricultural products. The state strongly promotes the construction of safe, pollution-free and environmentally-friendly green agricultural products cold storage. The applicable storage temperature of cold storage for agricultural products is +15°C~+8°C, +8°C~+2°C, and +5°C~-5°C, respectively. Meet the needs of different users. The scope of application of agricultural products cold storage: fruits, vegetables, flowers, food, beer, food, seeds, tea, cold drinks, agriculture, medicine, meat, poultry, aquatic products, hotels, hotels, dairy products, institutions, supermarkets, agencies, enterprises Institutions.
I. Selection and use of modern cold storage facilities in agricultural production areas
1. What is fresh-keeping, preservation, preservation, or preservation? The main content is preservation, that is, to maintain the original quality and freshness of some agricultural products for a long period of time, that is, fresh agricultural products that are stored for a period of time After that, it is still freshly picked or near the fresh state and quality just after picking.
2. The relation between temperature and freshness preservation of agricultural products After harvesting, agricultural products are still a living body. During the storage process, it needs to maintain its life, and it is necessary to cut off its own storage nutrition, and gradually lose its nutritional value and live quality. In addition, insect pests can use the stored nutrients of agricultural products as food. As a result, the agricultural products will spoil and deteriorate and lose their freshness and food value. How to ensure that the livelihood of agricultural products after harvesting keeps the nutrition and live quality, and temperature is the most important influencing factor. Generally speaking, the lower the temperature is, the less nutrient consumption of the product, the worse the pest and disease damage, and the longer it takes to maintain fresh quality. At the same time, the smaller the temperature change, the better the preservation effect. Preservation temperature is not unrestricted low, because the temperature is so low that the product can not endure, cold injury or freezing injury will occur. Therefore, preservation requires a relatively stable and suitable low temperature condition. The optimum preservation temperature for most agricultural products is around 0°C.
3. Maintaining the optimum temperature for keeping fresh produce in storage is changing with the season of the year and the time of day. Most of the seasons for conventional agricultural products are high in temperature in the season of normal cultivation and harvesting, and the amplitude of day and night changes greatly. Fresh products suitable for storage. Many simple solutions are to find a place where the natural temperature is relatively low and stable to store agricultural products to extend the shelf life of the product, such as caves, crypts, shady areas, etc. These methods can not arbitrarily control the temperature, the preservation effect is poor, and the preservation period is also Shorter. According to the temperature required for long-term storage and preservation of products, the final solution still depends on artificially creating a relatively stable low-temperature condition, that is, through mechanical equipment and electronic equipment, within a certain range, artificially control the temperature, common cold storage This is such a facility. After harvesting of fruits and vegetables in general, it must be cooled as soon as possible (pre-cooled to about 0°C), preferably in the cold storage within 1-2 days after harvesting. Because the harvested fruit is delayed by 1 day at a temperature of 21°C, it will reduce the shelf life of 10-20 days at 0°C. Therefore, the fruit that has been sorted and selected after harvesting should be quickly cooled to within 3-5 days after entering the freezer. Storage at -1-0°C.
4. Management of stored fruits in cold storage The management of stored fruits in cold storage is mainly to regulate and control the temperature, humidity and gas composition of the cold storage environment. Temperature adjustment is based on different varieties, in different periods of the temperature requirements, control the cold storage refrigerant evaporation rate to control the cold storage temperature. Cold storage is often caused by frost in the cooling pipe system, which hinders heat conduction and affects the cooling effect. Due to frost, the humidity in the cold storage room is too low. Therefore, the temperature should be defrosted regularly, and the humidity of the cold room should be adjusted in time by wet or spray. The ventilation of the cold storage should be carried out at night. If there is too much accumulation of carbon dioxide in the cold storage, an Air Purifier can be installed, or it can be absorbed by 7% caustic soda.
Second, fruits and vegetables keep cold storage knowledge Cold storage of fruits and vegetables, generally refers to the use of various equipment, refrigeration, can be controlled and maintain a stable low-temperature facilities. Its basic components are: refrigeration systems; electronic control devices; warehouses with certain insulation properties; ancillary buildings, etc. The refrigeration system mainly includes a variety of refrigeration equipment. The refrigeration equipment is the heart of the cold storage. It produces a cooling capacity and ensures the cold source supply in the warehouse. The electronic control device is the brain of the cold storage. It directs the refrigeration system to ensure the supply of cold. The warehouse with certain thermal insulation properties is a place for storing fresh agricultural products. Its role is to maintain the stability of the low-temperature environment. It is usually referred to as thermal insulation. The good thermal insulation structure of the warehouse can minimize the leakage of refrigeration equipment manufacturing to the outside. In other words, it is to minimize the leakage of heat from outside the library to the inside of the warehouse. This is also the main reason for cold storage and general housing. the difference.
Third, preservation of fruits and vegetables
1. The selection and sorting of fruits and vegetables before they are put into the warehouse should be carefully performed one by one. The purpose is to remove fruits and vegetables with mechanical injury, insect injury or maturity. Because fruits and vegetables contain a lot of water and nutrients is a good medium for microbial life. Microorganisms invade the fruits and vegetables in the way that the fruits and vegetables that are contaminated by microorganisms in the wounds of the mechanical or vegetable wounds or insects will soon be completely rotted and deteriorated. Fruits and vegetables of different maturity should not be preserved together. Because mature fruits and vegetables will be over-aged after being preserved for a period of time, their characteristics are that the fruit becomes soft and will start to rot. Some fruits and vegetables that have been selected for good quality and can be refrigerated over a long period of time should be wrapped in paper one by one and packed or basketed. The paper used for wrapping fruits and vegetables should not be too hard or too thin. It is best to use paper that has been treated with chemicals that do not have any adverse effects on fruits and vegetables. Fruits with handles should pay special attention when packing and baskets. Do not press the fruit on the surrounding fruit so as not to break the fruit peel. During the entire selection process, special care must be taken with care in order to prevent injuries due to careless work. 2. After fruits and vegetables are put into storage, measures should be taken to cool them down. After harvesting, fruits and vegetables should be cooled in the raw material production area in time to cool the internal heat of fruits and vegetables. Cooled fruits and vegetables can be directly refrigerated when they are transported to refrigerators in a refrigerator. If the uncooled fruits and vegetables from the raw materials' place of production enter the cold room, gradually reduce the temperature to prevent certain physiological diseases from occurring. 3, different types of fruits and vegetables should be controlled at their optimum temperature for storage because different types of fruits and vegetables it can tolerate the ability of low temperature is not the same as the inappropriate low temperature and freezing, will affect the fruit's normal physiological function caused by flavor quality The change or the occurrence of a physiological disease, which is detrimental to storage. Therefore, high-temperature storage of fruits and vegetables should be controlled according to different types of storage temperature. 4. Humidity regulation Fruit and vegetables contain a lot of water, which is a necessary condition to maintain the fruit's vitality and fresh quality. Fruits and vegetables after picking can no longer obtain the supply of moisture from the mother, and gradually evaporate water during long-term storage. Most fruits and vegetables have a clear symbol of the decline in freshness such as withering when their dry consumption and weight loss exceeds 5%. In particular, it is impossible for a fruit to be restored to its original state after equivalent consumption of 5%. The evaporation of fruits and vegetables on the one hand is due to the respiration of a part of the water, the other is the storage environment, the air humidity is too low causing the fruits and vegetables withered, reducing the value of the goods. Therefore, the humidity of the high-temperature library needs to be well adjusted. The general requirement is 85% to 90%. If the humidity is too low, the automatic sprayer can be used in front of the blower and the fine mist can be sent into the air in the storeroom to humidify the air with the cold air. Without an automatic sprayer, sprinkle some clean water on the floor or place a wet mat on the packaging container to increase the relative humidity in the freezer. However, if the humidity is too high, the surfaces of fruits and vegetables are too moist, and sometimes the water droplets are condensed to create conditions for the growth of microorganisms. Fruits and vegetables are rotted easily. At this time, dry lime, waterless green calcium, or dry charcoal can absorb moisture in the warehouse. The temperature and relative humidity of the high-temperature freezer should be kept as stable as possible without large fluctuations, otherwise it will stimulate the respiration of fruits and vegetables to increase consumption, and the "sweating" of fruits and vegetables will reduce its storage.
IV. Technical Features of Cold Storage of Fruits and Vegetables (1) Features
1 Without refrigeration equipment, only a few wind turbines are used, the investment is small, and maintenance and management costs are low. Compared with common mechanical refrigeration plants using Chloride or ammonia refrigeration, they save more than 90% energy without any pollution.
2 The cold source in the reservoir comes from ice water, which has stable low temperature, high humidity, good preservation quality and long shelf life.
3 high degree of automation, easy management.
4 It is appropriate to build reservoirs in regions with annual average temperatures below 13~C and minimum winter temperatures below -8°C. The lower the temperature, the better.
(2) Performance indicators
1 Without any mechanical refrigeration equipment, the use of natural cold source, in the summer outside the temperature of the library up to 40 °C, the winter outside the library temperature dropped to -18 °C place, the library temperature can always be maintained at 2-3 °C Cold state.
2 This kind of fresh-keeping storage that uses natural cold sources without mechanical refrigeration can be built in areas with an average annual temperature of -2-13°C.
3 Anniversary temperature can be maintained at the low temperature needed for fresh fruits and vegetables, and the temperature can be automatically adjusted at 1-10°C.
4 The relative humidity in the library can always be kept above 90%, which is almost impossible to achieve for ordinary mechanical cold storage.
(3) Scale form
1 Storage capacity: 100-5000 tons.
2 storage species: apples, pears, peaches, grapes, cauliflower, green peppers and other fruits and vegetables.
3 Building area: 150-10000 square meters, according to the storage amount, 1 square meter building area can store 0.7-10 tons of fruits and vegetables.
(4) Architectural forms: Since the fresh-keeping library should use natural cold sources, it is necessary to greatly reduce the cost of building the reservoir in places where the climate is cold or where caves can be used according to the conditions for site construction.
5Management personnel: Because there is no complicated refrigeration equipment, the temperature can be adjusted automatically. The storage of 100-5000 tons of fruits and vegetables requires only 2-8 managers.
Fifth, the use of cold storage should be noted when the preservation of 1, the use of fresh cold storage technology, control the temperature in a cold storage is the key. As a short-term storage of clean food products, the general cold storage temperature should be controlled at 2 ~ 4 °C can be for cold-tolerant vegetables can be placed in a 5 ~ 7 °C cold storage, or take cover and other insulation measures to prevent vegetables Frozen. Easy-aging vegetables should be placed in a bank of around 0°C. In order to ensure the quality of the finished dishes, to avoid severe temperature changes, increased respiratory metabolism, vegetable dressing and coating should also be carried out at 2 ~ 5 °C conditions. 2. Humidity In order to ensure the freshness of vegetables and reduce dehydration and wilting, the humidity during storage is generally controlled at 80% to 95%. And in the storage process, according to the amount of storage and the temperature between the warehouse, pay attention to ventilation at any time. 3, appropriate drying for vegetables, mushrooms, onions, ginger and other surface moisture content of the larger species, must be properly drying before entering the warehouse, reducing the moisture overlying the vegetables on the surface, to extend the storage period. 4, to prevent stacking vegetables into the library should be neatly placed on the shelves, or hiccups placed in the library, to prevent excessive stacking pressure on the vegetables caused by mechanical damage or fever, causing the decline in the quality of vegetables. VI. Advantages of Sheng Xue's agricultural products cold storage modernization 1. Computer intelligent control of agricultural products cold storage storage Cold storage computer intelligent control system: The cold storage operating system uses a PC for intelligent program control, and has historical records and printing functions. It adopts imported and domestically-made high-quality and well-known brand electrical components, which are well-designed, with excellent performance, beautiful appearance, and multiple electrical protection functions. 2, high efficiency Air Cooler agricultural products cold storage cold storage efficient air cooler: DL type air cooler is a kind of cooling and cooling equipment for cold storage, it has a compact structure, light weight, does not take advantage of the cold storage area, etc., and nature Compared with convection pipes, it can cool the stored food quickly and improve the freshness of stored foods. 3, the material of the new library using rigid polyurethane or polystyrene foam insulation sandwich panels, high-pressure foaming process with a single injection molding, can be made of various lengths, specifications, to meet the different requirements of the majority of users. Its characteristics are: heat insulation performance, light weight, high strength, corrosion resistance, anti-aging, beautiful appearance. Types of cold storage panels are: colorful steel, salted steel, stainless steel, embossed aluminum and so on. 4. Easy to install and disassemble Shengxue cold storage walls are all produced by a unified mold, connected by internal concave and convex grooves, convenient for loading and unloading, and the installation period is short. The small and medium-sized cold storage can be delivered within 2-5 days. The library can be freely combined according to user needs. , separate or increase, decrease. 7. The temperature and relative humidity of the cold room shall be determined according to the requirements of cold processing or cold storage of various types of foods. Generally, it can be selected according to the following table. The best storage of food frozen.
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