How does drying fish prevent spoilage?

Drying fish prevents spoilage by reducing the product's water activity. Foods with high water content are highly susceptible to deterioration caused by microbial contamination and enzymatic activity. By removing moisture through dehydration—using methods such as forced-air drying, vacuum drying, or freeze-drying—the concentration of solutes increases while the available water decreases.123

This reduction in water activity effectively inhibits the growth of spoilage microorganisms and slows down chemical reactions that would otherwise degrade the quality of the fish. If the water activity remains too high, as seen in some kippered fish products, spoilage organisms can continue to grow, leading to a shorter shelf life.14