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Wheat Gluten
Wheat gluten, a hydrophobic protein of wheat flour is considered to be globular
protein composed of a combination of polypeptide molecules. Wheat protein composed of two major components, i.e. gliadin and glutenin. Gliadin is soluble in 70%
ethanol while glutenin is not soluble (Gennadios and Weller 1990). Even though
wheat gluten can dissolve in aqueous solutions at low ionic strength of high or low
pH but is not soluble in water (Krull and Inglett 1971). It has been shown that wheat
gluten has interesting gel and film formation ability (Sun et al. 2009), acting as semi
permeable barrier to water vapor, oxygen and carbon dioxide molecules (Gontard
et al. 1996). Wheat gluten films could be thus applied as food coatings or edible
films on naturally gluten containing foods (e.g. bakery products) in order to slowdown mass transfer phenomena such as water and oxygen, which are known to
decrease the shelf life.
One of the main issues related to the utilization of wheat gluten films is their
inherent water sensitivity. The mechanical and the barrier properties are highly
modified in wet conditions due to water sorption and subsequent plasticization
(Gontard et al. 1996; Lens et al. 2003). Incorporating a hydrophobic phase constituted by edible lipids into the protein or polysaccharide matrix is considered one of
the most promising approaches for reducing water sorption and water transfer
through edible films. Recently, Rocca-Smith et al. (2016) reported that by the addition of a lipid phase reduced the water sorption, water affinity (hydrophilicity) and
water transfer of wheat gluten films. Moreover, by the lipid addition, mechanical
properties are also affected with a decrease in rigidity and, at high aw, an increase
in extensibility.
Legume
Legume proteins are called as “poor man's meat” due to their low price as compared
to animal proteins. Legumes contain a protein level 2–3 times higher than cereals,
ranging from 17 to 30% in chickpeas, lentils, dry peas, beans and 35–49.6% in soybeans (Boye et al. 2010). The 2 major storage proteins present in legumes are albumins and globulins (Gonzalez-Perez and Arellano 2009). Among them, globulins
have the largest share (about 70%) of total legume-based storage proteins. In recent
years, legume protein based edible films and coatings have acquired good attention
due to their nutritional value as well as carrier of antimicrobial, antioxidant and
other bioactives. Soy proteins are regarded as the most typical representative of
legume proteins owing to high level of protein and decent functional characteristics.
Soybean protein materials are suitable for edible coatings because of their low permeability to oxygen and carbon dioxide, and reasonable cost (Kang et al. 2013). It
has been demonstrated that soybean protein materials combined with other materials have been used to prolong the shelf life of fresh-cut egg plants and walnut kernels (Ghidelli et al. 2014; Kang et al. 2013). In addition, soy protein-gelatin films
could also act as carrier of different bioactives use for preservation of food (Denavi
F. Jhan et al.
Wheat Gluten
Wheat gluten, a hydrophobic protein of wheat flour is considered to be globular
protein composed of a combination of polypeptide molecules. Wheat protein composed of two major components, i.e. gliadin and glutenin. Gliadin is soluble in 70%
ethanol while glutenin is not soluble (Gennadios and Weller 1990). Even though
wheat gluten can dissolve in aqueous solutions at low ionic strength of high or low
pH but is not soluble in water (Krull and Inglett 1971). It has been shown that wheat
gluten has interesting gel and film formation ability (Sun et al. 2009), acting as semi
permeable barrier to water vapor, oxygen and carbon dioxide molecules (Gontard
et al. 1996). Wheat gluten films could be thus applied as food coatings or edible
films on naturally gluten containing foods (e.g. bakery products) in order to slowdown mass transfer phenomena such as water and oxygen, which are known to
decrease the shelf life.
One of the main issues related to the utilization of wheat gluten films is their
inherent water sensitivity. The mechanical and the barrier properties are highly
modified in wet conditions due to water sorption and subsequent plasticization
(Gontard et al. 1996; Lens et al. 2003). Incorporating a hydrophobic phase constituted by edible lipids into the protein or polysaccharide matrix is considered one of
the most promising approaches for reducing water sorption and water transfer
through edible films. Recently, Rocca-Smith et al. (2016) reported that by the addition of a lipid phase reduced the water sorption, water affinity (hydrophilicity) and
water transfer of wheat gluten films. Moreover, by the lipid addition, mechanical
properties are also affected with a decrease in rigidity and, at high aw, an increase
in extensibility.
Legume
Legume proteins are called as “poor man's meat” due to their low price as compared
to animal proteins. Legumes contain a protein level 2–3 times higher than cereals,
ranging from 17 to 30% in chickpeas, lentils, dry peas, beans and 35–49.6% in soybeans (Boye et al. 2010). The 2 major storage proteins present in legumes are albumins and globulins (Gonzalez-Perez and Arellano 2009). Among them, globulins
have the largest share (about 70%) of total legume-based storage proteins. In recent
years, legume protein based edible films and coatings have acquired good attention
due to their nutritional value as well as carrier of antimicrobial, antioxidant and
other bioactives. Soy proteins are regarded as the most typical representative of
legume proteins owing to high level of protein and decent functional characteristics.
Soybean protein materials are suitable for edible coatings because of their low permeability to oxygen and carbon dioxide, and reasonable cost (Kang et al. 2013). It
has been demonstrated that soybean protein materials combined with other materials have been used to prolong the shelf life of fresh-cut egg plants and walnut kernels (Ghidelli et al. 2014; Kang et al. 2013). In addition, soy protein-gelatin films
could also act as carrier of different bioactives use for preservation of food (Denavi
F. Jhan et al.