11. Delivery of Food Additives and Antimicrobials Using Edible Films and Coatings

Functional efficiency of edible films and coatings strongly depends on the nature of film components and physical structure. Choice of a film-forming substance and/or active additive depends on the desired objective, nature of the food product, and specific application. Thus, lipids or hydrophobic substances such as resins, waxes or some insoluble proteins are most efficient for retarding moisture transfer. On the contrary, water-soluble hydrocolloids, like polysaccharides and proteins, are not very efficient barriers against water transfer. However their permeability to gases is often lower than those of plastic films. Moreover, hydrocolloids usually provide better mechanical properties to edible films and coatings than lipids and hydrophobic substances. Therefore, combinations of desirable properties can be obtained through collective use of hydrocolloids and lipids to create composite films. Film-forming substances, particularly proteins, require film additives such as plasticizers to improve film resistance and elasticity, or emulsifiers, to increase hydrophobic particle distribution in composite emulsion-based edible films (Debeaufort et al. 1998).