Fish meat is rich in nutrition, not only because of its high protein content, easy digestibility, and its content of 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 for preventing cardiovascular and cerebrovascular diseases and promoting intellectual development. However, if the fish is made into canned fish, will its nutritional value change?
Fish is rich in protein and various nutrients, has a low acidity, and is particularly prone to breeding bacteria, so it must be sterilized at high temperatures and pressures of 115-121°C when canned. Such high temperatures have little effect on the protein but can cause a significant loss of B vitamins. Therefore, the vitamin B1 content in canned fish can drop to about half that of fresh fish and will further decrease during long-term storage.
However, every cloud has a silver lining. The high-temperature, high-pressure heating makes the fish bones crispy and soft, causing a large amount of calcium to be released. Therefore, the calcium content of canned fish is more than 10 times higher than that of fresh fish, and minerals such as iron, zinc, iodine, and selenium are not lost. So, eating canned fish has some significance for supplementing minerals. However, if the fish used for canning is a deep-sea fish contaminated with lead, mercury, etc., as the bones become crispy and soft, the pollutants will also be released in large quantities, increasing the harm to the human body. Compared with fish that are easily contaminated, such as tuna, shark, sea bass, swordfish, barracuda, marlin, and cod, salmon, trout, and yellow croaker are relatively safer.
According to different processing methods, canned fish is divided into categories such as braised, in tomato sauce, fried, steamed, smoked, in oil, and in water. In general, fish in water has a low fat content and can basically maintain the natural fatty acid ratio of fish, making it the most recommended choice. Using fish in water with seasonings, paired with vegetables, you can make a delicious salad. Products in tomato sauce have a higher salt content, but the acidity of the tomato sauce is beneficial for preserving B vitamins, making it a good choice as well. Although varieties such as smoked, fried, and braised have a rich flavor, after being fried, the Omega-3 fatty acids in the fish are destroyed, the fat content increases significantly, and most of the B vitamins are destroyed, resulting in low nutritional value; during the frying and smoking process, toxic and carcinogenic substances such as benzopyrene may also be produced, greatly reducing food safety. Canned fish in oil mostly has not been high-temperature fried or smoked, so its safety is relatively high.
The shelf life of canned fish is as long as 24 months, and many consumers believe this is because it contains preservatives. This is not the case. Canning is an important food processing method where raw materials are placed in a sealed container that has been exhausted, treated with high heat to kill various microorganisms and bacteria, destroy the activity of enzymes, and prevent external contamination and oxygen from entering, thereby allowing the food to remain stable and edible for a long time. Therefore, most canned fish do not contain preservatives, and consumers can eat them with confidence.
However, when eating canned fish, it is also important to note that you should not consume more than 2 cans per week (each can contains about 225 grams of fish); among them, fried and smoked fish should not exceed 1 can; pregnant women, nursing mothers, and young children should try not to eat it. People who love canned fish should pay attention to a balanced diet in their daily lives, eat more fresh vegetables, fruits, legumes, and tubers to improve their ability to resist pollution, and avoid the possible adverse effects on health from eating large amounts of canned fish for a long time.
When eating canned fish, note that you should not consume more than two cans per week.