Remember canned foods don't contain preservatives. Once opened, the contents of the can should be treated just as you would fresh food. Transfer any unused portion to a plastic or glass container, cover and store in the refrigerator. I'm concerned about food poisoning these days. This heating to a predetermined temperature for a specified time is so that each can becomes like a little pressure cooker ensuring that the organisms, or the bacteria called pathogens which cause food poisoning, are killed.
Canned foods have already been cooked during processing, so they are ready to eat as they are.
They only need to be re-heated if they are to be eaten hot. The AGAL studies showed that there is very little practical difference in the nutritional value of canned foods compared with their fresh equivalents. I'm on a restricted diet. CFIS has produced lists of canned foods and recipes to help construct diets which avoid ingredients associated with food sensitivities and intolerances. CFIS commissioned the Royal Melbourne Institute of Technology University to independently compare the costs and sensory appeal of canned foods with their fresh or frozen equivalent.