Unopened canned tomatoes are best when used within 12 to 18 months when stored at room temperature. While they are safe for consumption beyond this time period, the tomatoes can develop an undesirable metallic taste. Once opened, canned tomatoes are good for seven days if kept in a refrigerator.
Canned tomatoes are picked and processed at peak ripeness to ensure they stay flavorful even after months of storage. During the canning process, heat sterilization is used to sterilize the tomatoes and ensure their safety. This process cooks the tomatoes in their can, which renders them ready for direct addition in recipes.