Canned food plays an important role in daily life. However, people have certain misunderstandings about the manufacturing, preservation principles, nutritional value of cans, how to identify the quality of cans, and storage methods. Today, the editor will give you a detailed introduction to canned food:

1. Four major misunderstandings about canned food:

Myth 1: Canned food contains many preservatives, which are harmful to the human body Harmful to health.

Fact: The reason why cans can be stored for a long time without deterioration is entirely due to sealed containers and strict sterilization, and has nothing to do with preservatives. The principle of canning is very simple: first, fully heat the raw materials to kill all microorganisms; at the same time, fully heat and sterilize the packaging cans; then put the sterile food into sterile containers, seal them while they are hot; and finally heat and sterilize them. , after cooling, the volume of the air in the top gap of the container shrinks, creating a negative pressure. The originally sealed bottle cannot be opened, and it is impossible for outside bacteria to enter. After these processes, the food will naturally not spoil, so there is no need to add any preservatives. According to Hao Yu, secretary-general of the China Food Industry Standardization Technical Committee, "canned food contains preservatives" is actually a prejudice against canned food and misleads consumers.

Myth 2: Canned food is a convenience food, no different from instant noodles. It can only satisfy hunger but has no nutrition.

Fact: The canning process is very simple and generally only requires heating. More importantly, the heating temperature for canning is not too high, and sometimes it is lower than the temperature for cooking at home. Therefore, to a certain extent, the nutrient loss of canned food is less than that of home cooking. Generally speaking, using pasteurization, the processing temperature of canned meat and canned seafood will not exceed about 120°C; the processing temperature of canned vegetables and fruits will not exceed 100°C; and our daily home cooking Temperatures can easily exceed 200°C.

Myth 3: Cans are made from scraps.

Fact: In fact, cans are made from high-quality, good-looking ingredients. For example, most canned fruits are packaged in glass bottles or transparent flexible packaging. You can directly see beautiful and complete oranges, peaches, hawthorns, pineapples, etc. As for cans whose "contents" cannot be seen, if raw materials of questionable quality are used, it is likely to affect the quality of the batch. Few manufacturers will take this risk. Finally, China is the world's largest canned food producer, and its products are exported to the United States, the European Union, Japan and other countries around the world, with the export volume reaching 3 million tons. These countries have particularly strict inspections of food. The fact that Chinese cans are so popular in the international market can prove that the quality of cans is excellent.

Myth 4: Canned food, no matter how safe and nutritious it is, is not fresh as long as it has been processed!

Fact: First of all, the raw materials used in canned food are fresh. When making cans, in order to pursue lower costs and better taste, the freshest raw materials are selected in the most suitable season. Moreover, in order to save costs, regular canning manufacturers have their own raw material bases and build their production lines closest to the base. In this way, it is equivalent to "picking and cooking now" from your own backyard, which greatly shortens the process from picking, transportation to processing.

Although we can easily buy "fresh" fruits shipped from various places, they only look fresh but their nutrients are constantly being lost. Because any fruits and vegetables continue to "breathe" after being picked, some nutrients will continue to decrease. The whole process of canned fruits from raw material picking to processing does not take more than 6 hours. High-temperature heat treatment will stop or slow down the chemical reaction of nutrient loss and maintain the freshness and nutrition of the food. Take yellow peaches as an example. One day after picking, 30% of vitamin C will be lost, while canned yellow peaches only lose 10%. Therefore, canned fruits are fresher than "fresh" fruits transported over long distances.

2. Different groups of people choose different canned foods

Chinese nutrition experts believe that it is best to only eat canned food two or three times a week, and different groups of people have different preferences.

Children can eat canned fruits. Research shows that the nutritional value of canned fruit is similar to that of fresh fruit. However, due to the high sugar content, it is not suitable for the elderly, but it is very suitable for children.

First of all, canned fruits are relatively soft and are suitable for children with poor digestive function. Secondly, many fruits that are originally very sour, such as yellow peaches, become sweet and delicious after being canned. In fact, the fruit yogurt we eat is also made from canned fruit, so that the taste will not change and it will not go bad easily. Canned fruits can not only be eaten directly, but can also be easily made into delicious foods: yellow peach yogurt, rock sugar snow pear and white fungus soup, sugared hawthorn mixed with cabbage hearts, etc.

The old man prepare some canned fish. Fish is rich in nutrients, but it is troublesome to cook and has thorns, making it inconvenient for the elderly to eat. Canned fish can solve this problem very well. Because the bones of canned fish are already very crispy and a large amount of calcium has been dissolved, it is easier for the elderly to eat.

The housewife picks out some novel cans. Housewives can buy some novel canned food with "rare" ingredients and use simple methods to make "innovative dishes", such as white asparagus, chickpeas, olives, etc.

Canned vegetables are suitable for office workers. Office workers lead a fast-paced life and don’t have time to eat enough vegetables. Canned vegetables are very convenient to eat. With some ham, eggs, and meat fillings, you can make a nutritionally balanced meal, such as corn, green beans, ham fried rice, corn soup, water chestnut balls, etc.

3. Different materials, canned nutrients are different

Different nutrients have different properties. After the food is canned, their vitamin content will also change differently.

Carotene, lycopene, and calcium will increase. Both carotene and lycopene are very stable to heat and therefore will not be lost. And after being heated and cooked, their absorption rate will be greatly increased. The canning process also plays a "concentrating" role, so carotene, lycopene, etc. will not be lost, but will be increased. Studies have shown that the carotene content in canned carrots is 50% higher than that of fresh carrots, and the lycopene content in canned tomatoes is 1 times higher than that of fresh tomatoes. Minerals are also not afraid of heating, so the content does not decrease and sometimes increases. Take canned fish as an example. During the production process, the fish bones become crispy and soft, and a large amount of calcium is dissolved. Therefore, the calcium in canned fish is more than twice that of fresh fish!

Protein and dietary fiber will not be lost. The heating temperature of canned food does not exceed 120°C, which is similar to the temperature used to cook braised pork in a pressure cooker at home, so nutrients such as protein, minerals, dietary fiber, etc. can be preserved intact.

Sour foods cause less vitamin loss. The only things that are really lost in canned foods are some vitamins, especially vitamin C and folic acid. However, the nutrient loss of different canned foods is different. Generally, the loss of acidic foods is relatively small, such as tomatoes; while the loss of nearly neutral foods, such as peas and spinach, is greater; meat mainly loses thiamine.

4. Tips for purchasing high-quality cans:

1. There is no "oil trademark". Observe whether the packaging is complete, whether there are leaks, whether the can lids and bottle caps are rusted or scratched, and whether the trademark is soaked in oil.

2. Don’t buy “fat” ones. Observe the bottom of the can, the lid or the bottle cap. It is better if the can lid and bottle cap are slightly concave. If you find that the can lid or bottle cap is bulging outward, check it out. Don't buy it.

3. The sound is crisp and bright. If you hit the can lid with your hand, it is of high quality; if the sound is dull, it means it has deteriorated.

4. The trademark must be good. Complete. Observe the production date and shelf life of the product, and be cautious when purchasing products with incomplete trademarks or those that are close to their shelf life.