The global spread of the COVID-19 has had a significant impact on people's living, eating and other habits, and consumption habits have changed accordingly. The consumption concept of food purchase has also changed: the awareness of nutrition and health has been enhanced, and the awareness of material reserves has been improved. Canned food has been favored by many consumers recently because of its storage resistance. In order to cooperate with scientific epidemic prevention, the China canned food industry association specially issued canned food consumption tips, so that citizens can correctly understand canned food and reasonably consume canned food.
Canned food refers to the food that can be stored at room temperature for a long time without adding preservatives after the qualified raw materials are processed, canned, sealed, sterilized, cooled, or aseptically canned, and meet the commercial aseptic requirements. The origin of canned food began in the early 19th century. In order to ensure the demand of food supply, French Napoleon's army offered a large reward. French Apel invented a processing technology that can keep food from deterioration for a long time, and then produced the prototype of canned food, which has been gradually popularized from military to civilian.
1、 Canned food can achieve a long shelf life without adding preservatives
Canned food can be preserved for a long time, which mainly depends on the realization of canned processing technology. There are three key points: (1) heating and exhausting, vacuuming or filling with nitrogen, nitrogen and carbon dioxide mixture, which greatly reduces the content of oxygen in food and containers, and makes the potential microbial growth in containers stagnate; (2) Tightly sealed to block the access of air (oxygen) or microorganisms outside the container into the container; (3) Thermal sterilization makes the potential microorganisms in the container die due to heat treatment, physical or chemical action.
Canned food is safe by sterilization and sealing. The raw materials of food materials are sterilized at high temperature, which greatly kills the microorganisms in the tank and meets the requirements of commercial sterility. In addition, the packaging materials are usually packed with tinplate, which can isolate the external air and moisture, and can ensure the stability of product quality for a long time. Therefore, products produced in strict accordance with the canning process can achieve a long shelf life without adding preservatives at all.
2、 Five key points of canned food packaging containers
Due to the particularity of canned food processing technology, canned food has high requirements for product packaging containers, which need to meet the following five elements:
(1) Canned containers need to be non-toxic: since canned containers are in direct contact with food, they need to be non-toxic to ensure food safety.
(2) Good sealing: microorganisms are the main cause of food corruption. As a food preservation container, it needs to have reliable sealing performance to make the food no longer deteriorate due to external microbial pollution after sterilization.
(3) It has good corrosion resistance: because canned food has certain nutrients, salts, organic substances, etc., it is easy to decompose in the process of high-temperature sterilization, which intensifies the corrosion of containers. In order to ensure the long-term preservation of food, containers need to have good corrosion resistance.
(4) Carry and use: it should have certain strength and be convenient for transportation.
(5) Suitable for industrial production: in order to improve production efficiency, reduce costs and stabilize quality, canned food should be able to withstand various mechanical processing in the production process and meet the requirements of factory mechanization and automatic production.
3、 When shopping for cans, you should pay attention to the product packaging and observe the product shape
Because canned food has a wide variety of packaging forms, such as metal packaging, glass bottle packaging, flexible packaging, etc., the quality of canned food should be judged from the aspects of appearance, packaging, sensory quality, label, brand, etc. Normal metal cans should have complete appearance, no deformation, no damage, no rust points, and the bottom cover should be concave; The center of the metal cover of the glass bottle and can should be slightly concave downward. When viewed through the bottle body, its contents should be complete in shape, clear in soup, and free of impurities. Otherwise, it is not suitable to buy.
In addition, 1. Don't eat canned products: canned products refer to the expansion and bulge at the bottom and top of tin cans, which is one of the manifestations of can deterioration. The reason for the expansion of cans is that the sterilization of cans is not complete, and the internal food is polluted by microorganisms. Microorganisms take the food in the tank as nutrition to reproduce and produce gas. The gas accumulates to a certain extent to form can deformation. 2. Do not eat the products with air leakage and mildew: the packaging of canned products will be deformed due to improper handling, bumping and other reasons during storage and transportation. The sealing part of the tank cover will leak air, which will cause the products in the tank to contact with the outside air, and microorganisms will begin to multiply. Generally, mold will be found after the product is opened.
4、 If the opened canned food cannot be eaten at one time, it should be properly preserved. Canned meat, poultry and aquatic animals contain rich nutrients, which are not only delicious food, but also the substrate for microbial growth and reproduction. The meat and bone of canned meat become soft, and a large amount of calcium is dissolved, which is more conducive to the digestion and absorption of protein and bone calcium by the human body. After opening the can, the meat and soup in the can come into contact with the air and are easily polluted by microorganisms in the air. If you can't eat it all at once and don't store the remaining cans correctly, it will cause a large number of microorganisms to multiply and cause the cans to deteriorate. Fresh ingredients used in canned fruits and vegetables can greatly keep nutrients from losing. However, once the cans are opened, if the cans are made of tinplate, the tinplate will easily oxidize after encountering air, which will destroy vitamin C in the food. If they are not poured out and stored in the refrigerator, the remaining cans may deteriorate due to microbial pollution. Consumers will be in danger if they eat such meat or canned fruits and vegetables. Therefore, once the meat or fruit and vegetable cans are opened, if they can't be eaten at one time, the remaining canned food should be poured into enamel, ceramic or plastic food containers, sealed with fresh-keeping film for temporary storage, or stored in the refrigerator, but it needs to be eaten as soon as possible. If you can't eat all the sugar jam and jam cans at one time, you should cover the mouth of the cans or pour them into other containers, seal them with fresh-keeping film, and eat them within 2 to 3 days (you can store them for a few more days in autumn and winter), because the sugar content of these cans is generally 40% - 65%, which has antiseptic effect and is not easy to deteriorate. When storing this kind of can, you can cover the can and ensure that it is in a sealed state as far as possible, or pour it into other containers with covers and store it in the refrigerator, but it is not suitable to store it for a long time.
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