Recently, many articles complaining about canned food circulated in micro-letters, all of which mentioned: "In order to prolong the storage time and improve the taste, there must be no lack of preservatives, salt and sugar in canned food. Canned food almost completely destroys vitamins and proteins in processing, which greatly reduces the original nutritional value of food. Long-term consumption of canned food is not only not conducive to adequate nutrition, but also accelerates aging.

 

 

 

 

Network transmission article screenshots

 

 

 

Jiefang Daily Shangguan News reporter learned that rumors such as "canned food is full of preservatives" spread widely on the Internet every other time, and every time they spread, they arouse concern and discussion. Now, it's time to make it clear.

 

 

 

Canned foods are all preservatives?

 

 

 

Canned Food = Preservatives + Nutrition? Having been misunderstood for so many years, it's time to get rid of it! The principle of preservation of canned food is clearly explained, which has nothing to do with preservatives.

 

 

 

According to the article, the reason why canned food can be preserved for a long time without deterioration is entirely due to sealed containers and strict sterilization, without adding any preservatives. Because the principle of Canning is very simple: the raw material and the container are heated and sterilized separately, while the heat is sealed, then heated and sterilized; when cooled, the volume of air in the top gap of the container will shrink, resulting in negative pressure, making the sealed bottle more difficult to open, and the bacteria outside will not be able to enter. After these processes, the food will naturally not spoil, so there is no need to add preservatives.

 

 

 

Canned food is not nutritious?

 

 

 

This is not the case. Generally, pasteurization is used in canned meat and seafood. The processing temperature is about 120 C. The processing procedure after buying is very simple, just heating. Therefore, to some extent, the nutritional loss of canned food is less than that of home cooking (stir-fried vegetables can easily exceed 200 C). However, the processing temperature of canned vegetables and fruits will not exceed 100 C, and the nutrition is relatively well preserved.

 

 

 

Canned food accelerates aging?

 

 

 

The rumor that "eating canned food for a long time is not only not conducive to adequate nutrition, but also accelerates aging" is also too exaggerated. Zhang Jing, Director of Nutrition Department of Tongren Hospital in Shanghai, said that modern people do not regard canned food as a single dietary source. Even if there is a small amount of vitamin loss in the process of canned food production, the human body will also extract nutrition from other foods. In addition, there are many reasons for human aging, such as the aging of the body itself, imbalanced nutrition and sunshine, and not only caused by diet. In this way, there is no direct causal relationship between aging and canned food.

 

 

 

However, Zhang Jing reminded that the salt content of canned meat and the sugar content of canned fruit are indeed very high. It is OK to eat occasionally, but the total amount should be controlled.