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Emulsifying Properties
The amphiphillic nature of protein molecules is utilized to stabilize different types
of emulsions. The stability of the emulsions by utilizing proteins comes from the
fact that protein molecules concentrate at the oil and water interface; with lipophilic
portion in the non-polar phase (oil) and the hydrophobic portion in the polar (water)
phase (Wilde 2000). The stability is maximum when proteins form a solid viscoelastic structure which results in absorption, unfolding and formation of strong
interactions. These interactions are well correlated with emulsion stability. The different method by which unfolding of proteins can be obtained are thermal, enzymatic, radiation and ultrasonic treatment. Some researchers have used combination
of pH and heat treatment in order to change the native structure of protein molecule
to impart desirable functional properties. Moreover, the unfolding of proteins at
interfaces is influenced by the structure in solution, like flexible proteins will unfold
quickly and rapidly and hence lower the interfacial tension (Kinsella and Whitehead
1989; Mitchell 1986), whereas globular proteins unfold more slowly as they have
more intramolecular bonds stabilizing their structure (Wilde 2000). The unfolded
proteins tend to form stronger intermolecular interactions and stabilize against
coalescence very effectively (Mitchell 1986). Therefore, changing the structure of
proteins by various means has been used as a tool for improving protein functionality, probably by inducing a change in adsorbed conformation. Emulsifying properties of proteins are important in many food systems. The important emulsifying
properties of proteins include emulsion activity and emulsion stability. Emulsion
activity is defined as the ability of a protein to form an emulsion by adsorbing oil at
the oil-water-interface. On the other hand emulsion stability is the ability to stabilize
emulsion without forming coalescence and flocculation over a period of time. These
properties are important as they determine their ability to act as emulsifiers in various foods such as soup, sauce, confectionary product, and dairy products Karaca
et al. (2011). These properties are greatly affected by molecular size, surface hydrophobicity, net charge, steric hindrance and molecular flexibility. Apart from this it
has been observed that hydrophobic patches present on the surface of protein molecules are important for protein adsorption at the water oil interface during the formation of emulsion (Timilsena et al. 2016).
Film Forming Properties of Proteins
Biodegradable films developed from hydrocolloid materials are gaining tremendous interest due to their excellent mechanical, and comparable barrier properties.
Proteins are well known for their film forming properties because they are far better than the films developed from polysaccharides and lipids. As protein molecules
have unique structure due to the presence of 20 different monomers which are
responsible for providing a wide range of functional properties, especially a high
intermolecular binding potential. In addition to this the films formed from these
hydrocolloid materials are usually biodegradable and safe packaging materials
N. A. Mir et al.
Emulsifying Properties
The amphiphillic nature of protein molecules is utilized to stabilize different types
of emulsions. The stability of the emulsions by utilizing proteins comes from the
fact that protein molecules concentrate at the oil and water interface; with lipophilic
portion in the non-polar phase (oil) and the hydrophobic portion in the polar (water)
phase (Wilde 2000). The stability is maximum when proteins form a solid viscoelastic structure which results in absorption, unfolding and formation of strong
interactions. These interactions are well correlated with emulsion stability. The different method by which unfolding of proteins can be obtained are thermal, enzymatic, radiation and ultrasonic treatment. Some researchers have used combination
of pH and heat treatment in order to change the native structure of protein molecule
to impart desirable functional properties. Moreover, the unfolding of proteins at
interfaces is influenced by the structure in solution, like flexible proteins will unfold
quickly and rapidly and hence lower the interfacial tension (Kinsella and Whitehead
1989; Mitchell 1986), whereas globular proteins unfold more slowly as they have
more intramolecular bonds stabilizing their structure (Wilde 2000). The unfolded
proteins tend to form stronger intermolecular interactions and stabilize against
coalescence very effectively (Mitchell 1986). Therefore, changing the structure of
proteins by various means has been used as a tool for improving protein functionality, probably by inducing a change in adsorbed conformation. Emulsifying properties of proteins are important in many food systems. The important emulsifying
properties of proteins include emulsion activity and emulsion stability. Emulsion
activity is defined as the ability of a protein to form an emulsion by adsorbing oil at
the oil-water-interface. On the other hand emulsion stability is the ability to stabilize
emulsion without forming coalescence and flocculation over a period of time. These
properties are important as they determine their ability to act as emulsifiers in various foods such as soup, sauce, confectionary product, and dairy products Karaca
et al. (2011). These properties are greatly affected by molecular size, surface hydrophobicity, net charge, steric hindrance and molecular flexibility. Apart from this it
has been observed that hydrophobic patches present on the surface of protein molecules are important for protein adsorption at the water oil interface during the formation of emulsion (Timilsena et al. 2016).
Film Forming Properties of Proteins
Biodegradable films developed from hydrocolloid materials are gaining tremendous interest due to their excellent mechanical, and comparable barrier properties.
Proteins are well known for their film forming properties because they are far better than the films developed from polysaccharides and lipids. As protein molecules
have unique structure due to the presence of 20 different monomers which are
responsible for providing a wide range of functional properties, especially a high
intermolecular binding potential. In addition to this the films formed from these
hydrocolloid materials are usually biodegradable and safe packaging materials
N. A. Mir et al.