ABSTRACT
The diffusion of small molecules in food and food packaging materials is important in food processing operations, food product development, and food process control. It involves the transport of small molecules, such as sugars, organic acids, flavor components, salts, preservatives, and gases (e.g. oxygen, carbon dioxide). In addition, the transport of larger molecules, such as lipids, is of interest to food processing, such as oil extraction. The transport of solutes is of fundamental importance to the physical separation processes, such as solvent extraction (e.g. sugar/water), ion exchange (e.g. de-acidification and de-bittering of juices), reverse osmosis, and ultrafiltration. Mass diffusivity is the basic component of permeability of packaging films and food coatings, which are used as barriers to water, oxygen, and carbon dioxide transport in food materials.
