Why do meat and fish stay fresh in cans?

Canned meat and fish stay fresh because of a process called canning, which involves heating the food in a sealed container to a high enough temperature to kill any microorganisms, such as bacteria, yeasts, and molds, that can cause food spoilage. The heat treatment also helps to inactivate enzymes in the food that can cause deterioration and quality loss.

Once the food is heated and sealed, the absence of oxygen inside the can prevents the growth of aerobic bacteria, which are microorganisms that require oxygen to thrive. The low oxygen levels also help to inhibit the growth of other types of spoilage microorganisms.

In addition, the airtight nature of the sealed can prevents recontamination of the food after processing, ensuring that it remains safe and fresh for an extended period of time. The sealed container also protects the food from external environmental factors, such as light and moisture, that could potentially affect its quality and safety.

The canning process also aids in preserving the flavor and nutritional value of the food by minimizing exposure to oxygen and other elements that can cause degradation. As a result, canned meat and fish can retain their nutritional content and taste for a longer time compared to fresh or unpackaged counterparts.

Overall, the combination of heat treatment, airtight sealing, and the absence of oxygen creates a shelf-stable environment that effectively preserves the freshness and quality of canned meat and fish, allowing safe consumption for an extended period without refrigeration.