Canned food is a model for military science and technology to be converted to civilian use.

 

Canned food plays an irreplaceable role in military, rescue, exploration and other fields.

 

Canned food is one of the most important inventions in the history of human food industry, and also a model of military science and technology for civilian use.

 

Napoleon, the French emperor, opened up his territory in Europe and the battlefront was too long. In order to solve the problem of military logistics supply, he offered a reward of 12,000 francs to solve it.

 

At that time, it was a huge sum of money, about the same as a person's lifetime income.

 

 

 

A Frenchman named Nicolas Appel came up with a way to keep food in a wide-mouthed glass bottle, first cooked and then sealed. This was the earliest canned food.

 

After that, Peter Durham invented tinplate cans, which further improved the storage and portability of cans.

 

Despite Napoleon's defeat, the invention of cans is still an important logistical material for the army and exploration teams.

 

 

 

 

 

 

Later, the convenience, storage resistance and nutritional delicacy of canned food were widely recognized by the society, and gradually became a popular delicacy.

 

Decades ago, when visiting relatives and friends, the owner would be very happy if he brought several cans of fruit.

 

If you have canned lunch meat, it's a gift.

 

But with the development of food storage, transportation and processing technology, fresh ingredients are within reach. People begin to dislike this former partner. The most important thing is that it is "full of preservative flavor".

 

Indeed, canned food has a shelf life of six months or even more than a year. If it stays for such a long time, is it added?

 

 

 

 

 

[Commercial sterility]

 

Canned products are made of fruits, vegetables, edible fungi, meat or aquatic products through processing, canning, sealing, sterilization and other processes.

 

Whether tinplate canned meat or glass canned fruit, although the production process is slightly different, the core is sterilization.

 

The early sterilization method was water boiling (100 degrees), then calcium chloride solution boiling (115 degrees), and then high pressure steam sterilization (121 degrees).

 

According to the current national standards, canned food needs to meet the requirements of "commercial sterility".

 

 

 

Commercial aseptic test should be done before canned products leave factory. By simulating storage at room temperature, we can see whether canned products will be deteriorated by swelling, bulging and other phenomena.

 

Through the microbial culture experiment, we can see whether there is the possibility of microbial reproduction.

 

"Commercial sterility" does not mean that there is absolutely no bacteria, but that there are no pathogenic microorganisms.

 

Some cans may contain a small amount of non-pathogenic microorganisms, but they do not reproduce at normal temperatures.

 

For example, there may be a small amount of fungal spores in canned tomato sauce. Because of the strong acidity of tomato sauce, these spores are not easy to reproduce, so preservatives can be avoided.

 

 

 

[Canned with preservatives]

 

Most cans do not need preservatives, except for individual cans.

 

For example, canned bayberry needs propionic acid, canned mushrooms, canned cereals can use Streptococcus lactis.

 

In addition to traditional cans, soft cans are now more popular in industry. Their production process is basically similar to that of ordinary cans, but the packaging materials have changed. Common ones include nylon film, polyethylene film, aluminum foil, etc. Some of them also add preservatives according to the process requirements.

 

 

 

It should be emphasized that these cans, even with preservatives, are not a problem. On the one hand, they have technological needs. On the other hand, adding them according to the national standards will not affect health.

 

Adding preservatives is also beneficial to maintaining the taste and nutrition of food, because it does not need to be heated at high temperature for a long time.

 

Canned meat (such as lunch meat) usually contains nitrite, although it can be used as a preservative, but here is another function.

 

Nitrite can combine with myoglobin to form a beautiful red color, so it can protect the color.

 

 

 

[Canned nutrition]

 

Another reason why canned food has been criticized is that nutrition is destroyed. Have you ever thought that what is in canned food is not nutrients?

 

Canned food after high temperature treatment, of course, the nutrition will be worse than fresh food, but it does not mean that there is no nutrition.

 

Protein, fat, minerals, dietary fiber and other nutrients will not change substantially because of the sterilization process. The main loss in canning processing is vitamins, such as vitamin C, vitamin B and folic acid.

 

But cooking and frying can destroy vitamins more or less, and you can't eat them?

 

 

 

For a long time, Chinese people's prejudice towards canned food has affected its development at home, but Chinese canned food is very popular in the international market, and is exported to developed countries such as the United States, Russia, Germany, Japan and so on.

 

According to statistics, Americans eat 90 kilograms of canned food a year, 50 kilograms in Europe, 23 kilograms in Japan, and only 1 kilogram in China.

 

In addition, canned food still plays an extremely important role in the fields of travel, exploration, disaster relief, military logistics and so on.

 

So, if you have fresh food, you can eat fresh food. There is no fresh food or emergency. Canned food is a good choice.