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Why are fish sealed in airtight containers before canning?
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fish processing
Fish on a conveyor belt entering a processing plant, Newfoundland, Canada.
Fish are sealed in airtight, or hermetic, containers before canning primarily to prevent spoilage and ensure long-term preservation. This process serves two critical functions:
- Microbial Protection: The sealing process prevents new microorganisms from entering the container after the food has been sterilized by heat. By creating a barrier, the container ensures that the fish remains free from further microbial contamination.12
- Vacuum Creation: Sealing the containers, often after exhausting air, allows for the creation of a partial vacuum as the contents cool. This environment is essential for maintaining the integrity of the preserved product.1
In the context of fish processing, this hermetic seal is combined with high-temperature heating to kill existing microorganisms and inactivate degradative enzymes that would otherwise cause the flesh to spoil. Together, these steps allow canned fish to be stored safely for several years.2