While many commercial canners place "use by" or "best by" dates on their products, low-acid foods such as meat and seafood usually remain safe up to five years after canning, while high-acid foods such as fruits and vegetables remain safe for 12 to 18 months. Home-canned goods should generally be used within a year of preservation. Once opened, any canned food should be consumed immediately or refrigerated promptly.
Canned food safety depends on the structural integrity of the can. Any dents or rust have the potential of opening microscopic holes through the can's protective barrier, allowing bacteria or other contaminants access to the food within. Regularly inspect canned food stores for damage or corrosion, and remove any cans that show the potential for contamination. If a can begins to bulge, the food inside has gone bad and it should be discarded immediately.
When opening canned foods, examine the food inside carefully. If the food looks moldy or smells bad, discard it immediately. If the level of food inside the container seems too high or too low, it could indicate a leak in the container. Bubbles or discoloration on the surface of the food also indicate the presence of bacteria, mold or other toxins that render the food unsafe to consume.