Salt draws water out of meat through osmotic pressure
Salt curing works through osmosis: salt crystals on meat's surface draw water out of muscle cells toward the higher salt concentration. This water loss concentrates salt within the meat, dramatically lowering water activity (the amount of free water available to microorganisms). Pathogens like Clostridium botulinum, Salmonella, and E. coli require water activity above 0.93 to grow. Cured meat typically drops to 0.75-0.85, inhibiting virtually all foodborne pathogens.
The process takes time: salt diffuses inward slowly, and the strongest preservation requires allowing salt and drying to work for weeks or months. Traditional prosciutto and Serrano ham cure for 1-3 years, achieving extremely low water activity (0.65-0.75) and stable preservation without refrigeration.
Texture and flavor changes during curing
Water loss concentrates proteins and salts, intensifying flavor. The texture becomes denser and chewier as muscle cells shrink. Some cured meats undergo enzymatic breakdown during long aging: proteases from both the meat and salt-tolerant bacteria present on the surface break down proteins, producing free amino acids that contribute umami. The final product is shelf-stable at room temperature for months or years, depending on cure depth and storage conditions.