Fish is rich in nutrients, not only because of its high protein content, which is easy to digest and contains B vitamins and minerals such as calcium, zinc, selenium and iodine, but also because its fat is rich in omega-3 fatty acids, which are beneficial to the prevention of cardiovascular and cerebral vascular diseases and the promotion of intellectual development. However, if the fish is canned, its nutritional value will not change?

Fish is rich in protein and a variety of nutrients, acidity is very low, especially easy to reproduce bacteria, so do the canned food to be sterilized at 115-121 ℃ under high temperature and pressure. Such high temperatures have little effect on the

protein, but will cause a large loss of B vitamins in it. As a result, the vitamin B1 content of canned fish can fall to about half that of fresh fish, and can be further reduced in long-term storage.

However, everything has its advantages and disadvantages. High-temperature and high-pressure heating makes the fish bones crispy and soft, allowing a lot of calcium to leach out. As a result, the calcium content of canned fish is more than 10 times higher than that of fresh fish, and there is no loss of minerals such as iron, zinc, iodine, and

selenium. Therefore, eating canned fish is of some significance for mineral supplementation. However, if the fish used for canning is deep-sea fish that has been contaminated with lead, mercury and other pollutants, the pollutants

will also be leached out in large quantities as the bones become crispy and soft, increasing the harm to the human body. Compared with tuna, shark, sea bass, swordfish, pike, marlin, cod and other easily contaminated fish, salmon, trout and yellowtail are safer.

According to the different processing methods, canned fish is divided into categories such as braised, eggplant sauce, freshly fried, steamed, smoked, oil-soaked and water-soaked. In general, water-soaked fish is the most worthwhile variety as it is low in fat and can basically maintain the natural

fatty acid ratio of fish. Use water-soaked fish with seasonings and vegetables to make a tasty salad. Ketchup-based products are higher in salt, but the acidity of ketchup is good for the preservation of B vitamins

and is a better choice. While smoked, fresh fried and braised varieties, although rich in flavor, but after frying, fish omega-3 series of fatty acids were destroyed, fat content rose substantially, the vast majority of B vitamins

Partially destroyed, the nutritional value is not high; fried and smoked in the process may also produce benzo(a)pyrene and other toxic carcinogens, so that the food safety is greatly reduced. Most of the canned food in oil does not undergo high-temperature frying and smoking, and its safety is

higher.

The shelf life of canned fish is up to 24 months, and many consumers think this is because it contains preservatives. This is not the case. Canning is an important class of food processing methods, that is, the raw materials are placed in the exhaust airtight capacity

The device, with high temperature processing, kill a variety of microorganisms and bacteria, destroy the activity of enzymes, to prevent outside contamination and oxygen into the food so that the long term to maintain a stable and edible state. Therefore, most of the canned fish are not added

added preservatives, consumers can feel safe to eat.

But eat canned fish should also pay attention to, the best not more than 2 cans per week (each can contains about 225 grams of fish); which, fried fish and smoked fish is best not more than 1 can; pregnant women, lactating mothers and young children try not to eat. People who love to eat canned

fish, usually pay attention to a balanced diet, eat more fresh vegetables, fruits and beans, potatoes, to improve the anti-pollution ability, in order to avoid long-term eating a large number of canned fish on the health of the possible adverse effects.

Note when eating canned fish, it is best not to exceed two boxes per week.