Coating edible biopolymers

Biodegradable films made from edible biopolymers from renewable sources could become an important factor in reducing the environmental impact of plastic waste. Proteins, lipids, and polysaccharides are the main biopolymers employed to make edible films and coatings. Which of these components are present in different proportions and determine the properties of the material, as a barrier to water vapor, oxygen, carbon dioxide, and lipid transfer in food systems (Gomez-Guillen et al. 2002 and 2009). 

Coatings and edible films are used to protect food products and improve their quality and shelf life. There has been a great interest in production of edible films and coatings from biopolymers in recent years. The most widely used edible and biodegradable films are cellulose derivatives. 

Edible coatings are thin layers of edible biopolymers applied on the surface of foods as protective coatings. One of the benefits of using cellulose esters in coating is the control of viscosity properties. 

Edible films and coatings are produced from edible biopolymers and food-grade additives. Film-forming biopolymers can be proteins, polysaccharides (carbohydrates and gums) or lipids. Plasticizers and other additives are combined with the film-forming biopolymers to modify the physical properties or functionality of films. The composition of the film must be chosen according to specific food applications, the type of food products and the major mechanisms of quality deterioration. 

Edible films and coatings are thin materials made from biological macromolecules (biopolymers).1 The main biopolymers used in preparing biofilms are polysaccharides2 and proteins.3,4 Among the most studied polysaccharides are pectin, cellulose and derivatives, alginates, carrageenan, chitosan and starch.1 5... 

Torres, J.A., Mireles, C., and Savant, V.D. 1998. Two food application of biopolymers Edible coating controlling microbial surface spoilage and chitosan use to recover protein from aqueous processing wastes. In Imam, S.H., Greene, R.V., and Zaidi, B.R. (eds.). Biopolymers Utilizing Nature s Advanced Materials, American Chemical Society Symposium Series, No. 723. ACS Publications, Washington, DC, pp. 248-282. 

To summarize, cellulose applications in the packaging industry can be organized into three main topics. The first one is to extract cellulose from plants and use it directly to prepare composites. The second one is to produce cellulosic plastics like cellulose acetate, which are the best examples of biopolymers derived from renewable resources. The third one is to prepare cellulose coating materials, edible and non-edible films. Therefore, detailed discussions about each of these topics and processes are presented in this chapter along with many related subjects based on cellulose and its derivatives. 

A further interesting biotechnological application of natural polysaccharides is in the development and design of new biomaterial. Natural biopolymers possess the capacity to establish chemical and physical intramolecular interactions, resulting in a cohesive polymeric matrix able to form biofilms. These biofilms show specific properties (mechanical and barrier properties, transparency, biodegradability and biocompatibility) that make them suitable for applications in edible coating for food products and... 

Proteins and polysaccharides produced on an annual kiloton scale in the world have attracted extensive research attention as potentially the most significant eco-materials as well as edible and biodegradable films and coatings (Thakur and Thakur 2014a, b, c). Edible films made from polysaccharides and proteins act as excellent barriers to nonpolar substances such as O2, CO2, and lipid, particularly at low relative humidities. In contrast to synthetic polymers having a simpler and more random structure, biopolymers are complex molecular assemblies with precise and... 

Use of an edible coating with the required barrier properties for the food and subsequently use of biopolymers as primary packaging,... 

In the case of edible composite films and coatings containing a biopolymer and a lipid, the formulation requires to heat the lipid above its melting point, to homogenate both phases, degas, and cast on the plate or product surface, with the final evaporation of the solvent (Krochta, 2002). Some drying methods that have been studied include... 

Edible films and coatings can also provide grease/oil barrier. There are few works on oil barrier of edible films (Krochta, 2002). As known, hydrophihc edible films exhibit good grease/oil barrier. Thus, the apphcation of biopolymer coatings on paperboard can provide an alternative food apphcation for fast-food packaging and oily food product. 

Rhim, J.W. Increase in water vapor barrier property of biopolymer-based edible films and coatings by compositing with lipid materials. Food Sci. Biotechnol., 13, 528-535 (2004). 

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