Edible coating and film materials: lipids and lipid emulsions

Abstract

The need to reduce moisture losses in the food industry makes the use of lipids good candidates as ingredients of edible films and coatings. In general, lipid materials are usually combined with polysaccharides or proteins forming composite films and coatings to improve their integrity. The hydrophobic lipid component can form a continuous layer over the hydrophilic polysaccharide and protein phase, or it can be dispersed in the hydrophilic matrix to form dispersed-lipid films. In both bi-layer and emulsion films, the efficiency of lipid materials in the composite films and coatings depends on the nature of the lipid used (neutral lipids, fatty acids, waxes, and resins), and in particular on its structure, chemical arrangement, hydrophobicity, physical state such as solid or liquid, and on lipid interactions with the other components of the film, such as proteins and polysaccharides. Bi-layer films usually provide higher moisture barrier than emulsion films. However, issues such as delamination and the requirement of several steps in the formulation, makes emulsion films more suitable for food application. These composite hydrocolloid-lipid edible coatings have been successfully applied to meat, cereals, confectionaries, dried fruits, nuts, and fresh and fresh-cut fruits and vegetables to reduce moisture loss, sogginess, rancidity and staleness, loss of flavor, respiration rate, cracking, etc. Recently, the addition of natural active agents, such as essential oils, into the polymeric matrix is gaining attention to obtain desiderable antimicrobial and antioxidative packaging edible coatings for meet and fresh produce. However, it is necessary that all the ingredients must satisfy food safety regulations, which are different in each country.