The shelf life of canned fish is as long as 24 months, which many consumers think is because it contains preservatives. In fact, it is not. Canned food is a kind of important food processing method, which is to put raw materials in the closed container with exhaust gas and treat them with high temperature to kill various microorganisms and bacteria, destroy the activity of enzymes, prevent external pollution and oxygen from entering, so as to keep the food in a stable and edible state for a long time. Therefore, most canned fish are not added with preservatives, and consumers can eat them with confidence.

Fish is rich in protein and a variety of nutrients, with very low acidity, and it is particularly easy to reproduce bacteria. Therefore, when canned, it should be sterilized under high temperature and high pressure of 115-121 ℃. Such a high temperature has little effect on protein, but it will cause a large loss of B vitamins. Therefore, the vitamin B1 content of canned fish can be reduced to about half of that of fresh fish, and will be further reduced in long-term storage.