The solubility of the antimicrobial agents in the foods is a critical factor of antimi crobial release. If the antimicrobial agent is highly soluble in the food, the migration profile will follow unconstrained free diffusion, while the very low solubility creates the dissolution-dependent monolithic system. For example, when highly soluble potas sium sorbate was incorporated in packaging materials (e.g. plastic films or papers) and the antimicrobial packaging materials were used for semi-solid or high-moisture foods, such as paste, yogurt, fruit jelly, soft cheese and sliced ham, the potassium sor bate dissolved in the food immediately after packaging. The potassium sorbate con- centration increased very fast on the surface of the foods and the surface concentration decreased slowly as the potassium sorbate diffused into the food. Fast diffusion of the antimicrobial agents in the food decreased the surface concentration rapidly. The maintenance of the surface concentration is highly dependent on the release rate from the packaging materials (diffusivity of packaging materials) and the migration rat the foods (diffusivity of the foods). Since the flux of the release from the packaging materials decreases as the amount of antimicrobials in the packaging materials reduces