Different nutrients have different properties. When food is canned, their vitamin content varies.

Carotene, lycopene, and calcium will increase. Carotene and lycopene are all very stable to heat, so they will not lose. And after heating and boiling, their absorptivity will increase greatly. The process of making canned food will also play a role of "concentration". Therefore, carotene and lycopene will not only lose, but increase. The results showed that the content of carotene in canned carrot was 50% higher than that in fresh carrot, and the content of lycopene in tomato can be 1 times higher than that in fresh tomato. Minerals are not afraid of heating, so the content will not drop, and sometimes will increase. Take canned fish for example, because during the production process, fish bones become crisp and soft, and dissolve a lot of calcium, so the calcium in canned fish is more than 2 times that of fresh fish.

 

There is no loss of protein and dietary fiber. The heating temperature of the canned can not exceed 120 degrees centigrade, which is similar to the temperature of burning red meat in the high pressure pot at home, so the nutrients, such as protein, mineral, dietary fiber and so on, can be kept in good condition.

 

Acid food has less vitamin loss. Only some vitamins, especially vitamin C and folic acid, can be lost in canned foods. However, the nutritional losses of different canned foods are different, and usually acidic food losses are smaller, such as tomatoes; and the loss of food near the neutral is larger, such as peas and spinach; meat is the main loss of thiamine.