Is there no nutrients for canned food?
Many people think that the nutrition of canned food is even worse. But this is not accurate.
The production of cans is actually not complicated. The basic process is as follows: firstly heat the contents (food) and kill all the microorganisms; then fully heat the packaging containers (cans, bottles, etc.); then put the sterile food into a sterile container. In the end, the heat is sealed; finally, the heat is sterilized. After cooling, the volume of the air in the headspace of the container shrinks, and a negative pressure is generated. The originally sealed bottle can not be opened, and the bacteria outside cannot enter. In this way, the microorganisms inside are killed by high heat, and the outside microorganisms cannot find the door to enter, and the food will of course not be corrupted. If the sterilization is thorough enough, the seal is strong enough, not to mention two years, three years will not be bad, naturally no need to add preservatives. Making cans to heat the food twice will definitely lose some nutrients, but this loss may not be as big as everyone thinks.
Canned fruits and vegetables
Everyone is most worried about canned fruits and vegetables. The heating temperature of cans is generally not more than 120 degrees. The minerals in fruits and vegetables are not afraid of heating. The contents of potassium, calcium and magnesium are not reduced by sterilization treatment, and dietary fiber in fruits and vegetables is also retained. The main fear of heat in fruits and vegetables is vitamins, especially vitamin C, B vitamins, folic acid and so on. Some of the vitamins are broken down by heating, and some of the vitamins are lost because they are dissolved in canned soup and are thrown away when eaten. Therefore, the vitamins in canned fruits and vegetables do lose a part. However, these nutrients are not completely gone.
Other fat-soluble vitamins, such as beta-carotene, have little loss. Therefore, for some people who can't eat vegetables and fruits, canned fruits and vegetables can also be a good nutritional supplement, as long as it is not excessively sugared or pickled, it is better than not eating. Moreover, canned food is mainly for convenience, a little canned food at home, occasional emergency use, as a disaster relief reserve, or as a picnic food when going out, it is also good.
Why can the canned fruit be in a glass bottle and the canned meat in an iron box?
In fact, almost all canned foods can be packaged in metal cans. Moreover, glass jars are heavy, brittle, and costly. As a simple example, a 500ml metal can weighs about 20-40g, while a 500ml glass can weigh 200-350g. Therefore, glass-packed products are more expensive to transport than metal packaging, and it is not very convenient in actual production and transportation. Therefore, in countries with large canned food consumption such as Europe and the United States, most of the canned foods on the market are metal cans.
However, due to its transparent nature, glass jars have a good display effect on the food itself, which can improve the product selling phase. For countries in China where the acceptance of canned foods may not be very high and the consumption of canned foods is not very large, this can attract consumers. Therefore, some canned fruits will use glass bottles.
In general, glass jars are costly, and only good-looking foods use glass packaging when they need to attract customers. The canned foods such as meat and chicken noodle soup are sold after a long period of high temperature treatment. The relatively cheap and ugly metal cans are the best choice!