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et al. 2009). Other legume proteins have also been investigated for preparation of
edible films and coatings. Bamdad et al. (2006) prepared films from lentil protein
concentrate (LPC) with the addition of glycerine showed good mechanical properties and water vapor permeability in concomitant with good solubility. Kowalczyk
et al. (2014) prepared pea protein based films in combination with plasticizers
(glycerol and sorbitol) and films plasticized with sorbitol exhibited higher tensile
strength and elastic modulus. Kidney bean protein and chitosan based composite
films containing antimicrobial (nisin) were fabricated. Antimicrobial activity results
revealed that test bacteria were sensitive to composite films (Fan et al. 2014).
Gelatin
Gelatins are denatured protein, obtained from animal collagen protein through partial hydrolysis by acid or alkaline, or structural changes by enzymatic or thermal
degradation. Gelatin has been one of the most studied biopolymers due to its filmforming ability and it is used as an outer film to protect food from drying and exposure to light and oxygen (Arvanitoyannis 2002). Films formed from gelatin sources
as a primary biopolymer are more desirable to produce as they are of low cost and
easily available (Hanani et al. 2013). Gelatin films or coatings exhibit good transparency, mechanical and barrier properties and can be manufactured by extrusion or
casting processes (Hanani et al. 2013; Molinaro et al. 2015). It has been shown that
gelatins form clear, flexible, strong and oxygen-impermeable films in presence of
plasticizers when cast from aqueous solutions (Gennadios et al. 1994). Edible coatings based on gelatin reduce oxygen, moisture, and oil movement and serve as carriers of antioxidants or antimicrobial agents (Krochta and de Mulder-Johnston
1997). Gelatin films can act as good gas barriers but their hydrophilic nature also
results in poor water barriers. According to Gomez-Guillen et al. (2011) the main
factors affecting the physical and structural properties of gelatin are the molecular
weight distribution and amino acid composition, and these characteristics could
play a key role in the physicochemical properties of the resulting films.
Casein
Casein, a major class of protein found in milk, possesses a rheomorphic structure
with a high degree of molecular flexibility and large number of polar groups, all of
which provide for good film-forming properties. For these reasons, casein is considered as an excellent candidate for numerous applications such as paper coatings,
adhesives, and food packaging materials (Ma et al. 2015). Caseins form films from
aqueous solutions without further treatment due to their random-coil nature and
ability to hydrogen bond extensively. It is accepted that electrostatic interactions
also play a key role in the preparation of casein-based edible films (Gennadios et al.
1994). The casein films possess reasonably good strength and low permeability for
oxygen and other nonpolar molecules. Due to presence of polar functional groups,
Advances in the Application of Food Proteins and Enzymes
et al. 2009). Other legume proteins have also been investigated for preparation of
edible films and coatings. Bamdad et al. (2006) prepared films from lentil protein
concentrate (LPC) with the addition of glycerine showed good mechanical properties and water vapor permeability in concomitant with good solubility. Kowalczyk
et al. (2014) prepared pea protein based films in combination with plasticizers
(glycerol and sorbitol) and films plasticized with sorbitol exhibited higher tensile
strength and elastic modulus. Kidney bean protein and chitosan based composite
films containing antimicrobial (nisin) were fabricated. Antimicrobial activity results
revealed that test bacteria were sensitive to composite films (Fan et al. 2014).
Gelatin
Gelatins are denatured protein, obtained from animal collagen protein through partial hydrolysis by acid or alkaline, or structural changes by enzymatic or thermal
degradation. Gelatin has been one of the most studied biopolymers due to its filmforming ability and it is used as an outer film to protect food from drying and exposure to light and oxygen (Arvanitoyannis 2002). Films formed from gelatin sources
as a primary biopolymer are more desirable to produce as they are of low cost and
easily available (Hanani et al. 2013). Gelatin films or coatings exhibit good transparency, mechanical and barrier properties and can be manufactured by extrusion or
casting processes (Hanani et al. 2013; Molinaro et al. 2015). It has been shown that
gelatins form clear, flexible, strong and oxygen-impermeable films in presence of
plasticizers when cast from aqueous solutions (Gennadios et al. 1994). Edible coatings based on gelatin reduce oxygen, moisture, and oil movement and serve as carriers of antioxidants or antimicrobial agents (Krochta and de Mulder-Johnston
1997). Gelatin films can act as good gas barriers but their hydrophilic nature also
results in poor water barriers. According to Gomez-Guillen et al. (2011) the main
factors affecting the physical and structural properties of gelatin are the molecular
weight distribution and amino acid composition, and these characteristics could
play a key role in the physicochemical properties of the resulting films.
Casein
Casein, a major class of protein found in milk, possesses a rheomorphic structure
with a high degree of molecular flexibility and large number of polar groups, all of
which provide for good film-forming properties. For these reasons, casein is considered as an excellent candidate for numerous applications such as paper coatings,
adhesives, and food packaging materials (Ma et al. 2015). Caseins form films from
aqueous solutions without further treatment due to their random-coil nature and
ability to hydrogen bond extensively. It is accepted that electrostatic interactions
also play a key role in the preparation of casein-based edible films (Gennadios et al.
1994). The casein films possess reasonably good strength and low permeability for
oxygen and other nonpolar molecules. Due to presence of polar functional groups,
Advances in the Application of Food Proteins and Enzymes