Egg-protein-based films and coatings

Abstract

Increased use of synthetic polymers in various applications like packaging films and coatings has led to serious ecological problems due to their nonbiodegradability (Mathlouthi 1986). In consequence, natural biopolymers are attractive for innovative uses as "green" materials, considering their renewable and biodegradable nature (De Graaf and Kolster 1998). Thus, research aimed at the use of biodegradable polymers in technical applications has expanded considerably in the recent years (Cuq et al. 1998; Krochta and Mulder-Johnston 1997), not only to solve environmental problems associated with the use of synthetic polymers but also to find new markets for Western agriculture (over-) production. Naturally occurring biopolymers available for forming films and coatings fall generally into the categories of animal or vegetal proteins, polysaccharides (sometimes from microbial sources), lipids, and fats. These biopolymeric materials used in films and coating formulations are shown in Fig. 1. Until now, usual synthetic petrochemical polymers like polyolefins, polyesters, polyamides, or polypropylene are those mainly used in packaging applications because they are available in great quantities, at low cost, and present some favorable functionality characteristics such as good mechanical and physical properties. Nevertheless, compared to these nonbiodegradable polymers, biopolymers present the principal advantage of preserving the environment and of being obtained from renewable resources. Of late, films and coatings obtained from biopolymers also present specific properties relevant for technical applications. In this section, only films and coatings using proteins and in particular egg proteins will be presented. © Springer-Verlag Berlin Heidelberg 2007.