How does canning preserve fish for several years?

Canning preserves fish for several years through a process of sterilization and hermetic sealing that prevents spoilage. The process functions through the following key mechanisms:12

• Sterilization: Fish are placed in containers and heated to high temperatures for a specific duration. This thermal treatment kills microorganisms—such as bacteria, molds, and yeasts—that are present on the fish and inactivates degradative enzymes that would otherwise cause the food to spoil.12
• Hermetic Sealing: By sealing the containers so that they are airtight, the process prevents further microbial contamination from entering the package after the sterilization phase.12
• Vacuum Creation: During the canning process, air is removed from the container. Once the can is sealed, sterilized, and cooled, the contraction of the contents creates a partial vacuum within the container, which further aids in preservation.2

While this method is highly effective, it is important to note that sterilization does not eliminate every single microorganism. Consequently, if canned products are stored at excessively high temperatures, bacterial growth and gas production may still occur.1