223
thus reducing the pressures on landfill from plastic solid wastes. A large number of
animal protein sources like milk proteins, collagen, gelatin, keratin, and myofibrillar protein are readily available for the development of biodegradable films.
However due to rising global economic problems and consumer demands originated from health concerns, religious limitations and increasing trend of vegetarianism has recently arisen an interest in the usage of functional plant based proteins
as alternative to animal proteins in the food industry for the development of biodegradable films (Dormont 2002; Alonso et al. 2006; Karim and Bhat 2009). Among
plant sources the commonly used proteins sources are corn zein, wheat gluten, soy
protein, amaranth protein, sunflower, chestnut proteins. Pseudo cereal proteins
also are gaining popularity for the development of biodegradable films. The film
forming ability is also associated with some desirable functional properties,such
as barrier properties (i.e., water vapor permeability), mechanical properties (i.e.,
tensile strength, elongation, deformability, and elastic modulus) as well as microstructural properties (i.e., dough and fiber formation and texturizing capability)
(Wihodo and Moraru 2013). These functional properties are crucial on improving
the quality of food products, especially extending the shelf life of processed fruits
and vegetables coated with the films. Some researchers have used polysaccharides
in combination with proteins for the preparation of edible films however the applicability is limited due to their high water vapour permeability which is due to their
hydrophilic nature. To improve the water-barrier properties of hydrocolloid-based
films, lipid compounds are frequently incorporated into these structures causing a
decrease in the WVP values at the expense of a reduction in the tensile strength
and elasticity of the composite films (Morillon et al. 2002; Vargas et al. 2009). In
addition to this the good film forming properties of plant proteins as compared to
animal proteins makes them potential candidate materials for developing edible
films which would serve as an alternative to plastic packaging materials (Bräuer
et al. 2007).
In recent years bioactive films and coatings developed from proteins have
received increasing attention. Nowadays, packaging plays a decisive role in the
improvement of the shelf life of food products and new packaging materials derived
from renewable sources are being developed (Lin and Zhao 2007). The potential of
edible films to control gas transfer and to improve food quality, has received increasing attention from researchers and industry, possibly due to their numerous advantages over non-biodegradable plastic packaging films (Srinivasa et al. 2007). Edible
film or coating can be defined as a thin, continuous layer of edible material formed
or placed on or between foods or food components and poses no health hazard to
consumers (Bravin et al. 2006). In addition to this edible films or coatings can also
serve as a carrier of bioactive compounds, thus enhancing the functional properties
of the food product by conferring number of health benefits. Most frequently used
bioactive agents in edible films include lysozyme, oregano extract, chitosan, essential oils of clove, garlic and origanum, lactic acid (LA) and propionic acid (PRO),
chitooligosaccharides and natamycin (NA) as antimicrobial agents. Incorporation
of bioactive compounds to these films improves the functional properties such as
water vapour permeability as well as antimicrobial and antioxidant properties
Food Biopolymers: Structural, Functional, and Nutraceutical Properties: Food Proteins…
thus reducing the pressures on landfill from plastic solid wastes. A large number of
animal protein sources like milk proteins, collagen, gelatin, keratin, and myofibrillar protein are readily available for the development of biodegradable films.
However due to rising global economic problems and consumer demands originated from health concerns, religious limitations and increasing trend of vegetarianism has recently arisen an interest in the usage of functional plant based proteins
as alternative to animal proteins in the food industry for the development of biodegradable films (Dormont 2002; Alonso et al. 2006; Karim and Bhat 2009). Among
plant sources the commonly used proteins sources are corn zein, wheat gluten, soy
protein, amaranth protein, sunflower, chestnut proteins. Pseudo cereal proteins
also are gaining popularity for the development of biodegradable films. The film
forming ability is also associated with some desirable functional properties,such
as barrier properties (i.e., water vapor permeability), mechanical properties (i.e.,
tensile strength, elongation, deformability, and elastic modulus) as well as microstructural properties (i.e., dough and fiber formation and texturizing capability)
(Wihodo and Moraru 2013). These functional properties are crucial on improving
the quality of food products, especially extending the shelf life of processed fruits
and vegetables coated with the films. Some researchers have used polysaccharides
in combination with proteins for the preparation of edible films however the applicability is limited due to their high water vapour permeability which is due to their
hydrophilic nature. To improve the water-barrier properties of hydrocolloid-based
films, lipid compounds are frequently incorporated into these structures causing a
decrease in the WVP values at the expense of a reduction in the tensile strength
and elasticity of the composite films (Morillon et al. 2002; Vargas et al. 2009). In
addition to this the good film forming properties of plant proteins as compared to
animal proteins makes them potential candidate materials for developing edible
films which would serve as an alternative to plastic packaging materials (Bräuer
et al. 2007).
In recent years bioactive films and coatings developed from proteins have
received increasing attention. Nowadays, packaging plays a decisive role in the
improvement of the shelf life of food products and new packaging materials derived
from renewable sources are being developed (Lin and Zhao 2007). The potential of
edible films to control gas transfer and to improve food quality, has received increasing attention from researchers and industry, possibly due to their numerous advantages over non-biodegradable plastic packaging films (Srinivasa et al. 2007). Edible
film or coating can be defined as a thin, continuous layer of edible material formed
or placed on or between foods or food components and poses no health hazard to
consumers (Bravin et al. 2006). In addition to this edible films or coatings can also
serve as a carrier of bioactive compounds, thus enhancing the functional properties
of the food product by conferring number of health benefits. Most frequently used
bioactive agents in edible films include lysozyme, oregano extract, chitosan, essential oils of clove, garlic and origanum, lactic acid (LA) and propionic acid (PRO),
chitooligosaccharides and natamycin (NA) as antimicrobial agents. Incorporation
of bioactive compounds to these films improves the functional properties such as
water vapour permeability as well as antimicrobial and antioxidant properties
Food Biopolymers: Structural, Functional, and Nutraceutical Properties: Food Proteins…