How does salt preserve food?

Salt preserves food primarily by acting as an antimicrobial agent that inhibits the growth of spoilage and pathogenic microorganisms. It achieves this by controlling water activity within the food.12

By adding salt, the concentration of solutes in the food increases while the concentration of water decreases. This process reduces the water available for microbial activity. In techniques such as curing or pickling, salt draws moisture out of the food through osmosis, creating an environment that suppresses undesirable microbial growth. In fermentation, this suppression allows for the development of a favorable environment for desired microorganisms. Because high water content makes food susceptible to deterioration, reducing this availability is a fundamental principle in food preservation technology.234