This fact sheet focuses on commercially canned goods. For information on home canning, request HGIC 3040, Canning Foods At Home . Canning is an important, safe method of food preservation if practiced properly. The canning process involves placing foods in jars or cans and heating them to a temperature that destroys microorganisms that could be a health hazard or cause the food to spoil. Canning also inactivates enzymes that could cause the food to spoil.
Air is driven from the jar or can during heating, and as it cools, a vacuum seal is formed.
This vacuum seal prevents air from getting back into the product bringing with it microorganisms to recontaminate the food. Carefully check dented cans and jars for leakage and rust before buying. Cans and jars should be free of dents, cracks or bulging lids, which can indicate a serious food poisoning threat. Dusty cans or torn labels may indicate old stock. Also check for pull dates.