Composite edible films and coatings

GARCIA, M.A.; PINOTTI, A.; MARTINO,M.N.; ZARITZKY, N.E.

Edible films and coatings for food applications

Springer Science

Año: 2009; p. 169 - 210

Composite edible films and coatings can offer great potential to enhance food quality, safety and stability. They can control mass transfer between components of a product as well as between the product and the environment; the addition of antioxidants, antimicrobial agents, etc. in their formulations improves their performance. The unique advantages of edible films and coatings may lead to new product developments, such as individual packaging of particulate foods, carriers for different additives, and nutrient supplements. Film materials and their properties have been reviewed extensively in this book and previously. Composite films can be formulated to combine the advantages of each component. Biopolymers such as proteins and polysaccharides provide the supporting matrix and are good barriers to gases, while lipids provide a good barrier to water vapor. Plasticizers are necessary to enhance flexibility and to improve mechanical properties. The lipid component in the coating formulation can serve as a good barrier to water vapor while the hydrocolloid component can provide a selective barrier to oxygen and carbon dioxide and the necessary supporting matrix. As for synthetic polymers, composition, microstructure and functional properties of biopolymeric films determine their possible applications. Controlling film formulation allows tailoring the mechanical and barrier properties of these materials improving efficiency of packaged foods conservation. The study of the microstructure and interactions of the film components also provides an insight into, both for the fundamental aspects of material science and the practical point of view. Most of the methods used in the characterization of the solid state are based on the detection of its structural properties such as the crystalline-amorphous structure and on the thermodynamic changes. X-ray diffraction is probably the most important technique in observing properties of crystalline solid materials, polymers, and undoubtedly food materials. Thermodynamic changes can be evaluated by several calorimetric techniques and thermomechanical analysis. Again, the knowledge of thermodynamic state, possibilities of molecular mobility and phase transitions are important since they affect mainly the barrier properties, which in turn affect the performance of films under conditions of common use and abuse. The objectives of this chapter are to describe: a) the properties and possibilities of different film components in relation to their functionality, with special emphasis on film formulations based on starch, chitosan and methylcellulose, b) the common characterization methods of the coatings and films and c) some specific applications of this biomateriales.