The vitamin content of canned food also decreases slowly even when the cans are stored under cool conditions. In general, canned foods retain their nutritional value well. The approximate storage life of most canned foods is two to four years. Because of this uncertainty as to the true age of the food, a conservative recommended storage time of about one year is often given. You should mark the date of purchase on the container if it is likely to be stored for an extended period in the home.
Foods packaged in non-metal containers often have a shorter storage life and are date marked.
The contents of freshly opened cans and packages should be treated as though they were freshly cooked at home. Contamination is possible as soon as the container is opened. If not eaten at one meal, the remainder should be refrigerated. Once cans are opened some foods, especially fruit, fruit juices, and tomato products, should be placed in a clean plastic or glass container, covered and stored in the refrigerator. When these foods are stored in the opened metal can, tin and iron will dissolve from the can walls and the food may develop a metallic taste.