Protein emulsifier modification

The effective utilization of proteins in food systems is dependent on tailoring the protein s functional characteristics to meet the complex needs of the manufactured food products. Many food proteins require modification to improve such functional properties as solubility, foaming and emulsifying activity (EA). Reviews on classical food protein modifications for improved functionality are available in the literature (Means and Feeney, 1971 Feeney and Whitaker, 1977, 1982, 1986). 

There are numerous reports in the literature describing the effects of protein modification on their emulsifying properties. Stainsby [17] has classified these modifications as being chemical or enzymatic in nature. Chemical modifications are often performed to increase the charge and thereby the solubility of proteins. However, modifications are often very drastic, and it is unlikely that such modified proteins will receive regulatory approval for use in food in the near future. The work of Ponnampalam et al. [35] is a representative example of chemical modifications. In this study, oat proteins were either acy-lated or succinylated to modify approximately 35 and 75% of the... 

Effective Hamaker constant, 234 Emulsifying activity index, 186,188/ Emulsions, concentrated oil-in-water, effea of interdroplet forces on centrifugal stability, 229-245 Enhancers of taste. See Taste enhancers Enzymatic modification of soy proteins, 181-190... 

The following factors appear to control the emulsification properties of milk proteins in food product applications 1) the physico-chemical state of the proteins as influenced by pH, Ca and other polyvalent ions, denaturation, aggregation, enzyme modification, and conditions used to produce the emulsion 2) composition and processing conditions with respect to lipid-protein ratio, chemical emulsifiers, physical state of the fat phase, ionic activities, pH, and viscosity of the dispersion phase surrounding the fat globules and 3) the sequence and process for incorporating the respective components of the emulsion and for forming the emulsion. 

Parameters Related to the Whipping and Emulsifying Functions of Surfactants Prepared from Proteins by Enzymatic Modification (24)... 

Although whey protein concentrates possess excellent nutritional and organoleptic properties, they often exhibit only partial solubility and do not function as well as the caseinates for stabilizing aqueous foams and emulsions (19). A number of compositional and processing factors are involved which alter the ability of whey protein concentrates to function in such food formulations. These include pH, redox potential, Ca concentration, heat denaturation, enzymatic modification, residual polyphosphate or other polyvalent ion precipitating agents, residual milk lipids/phospholipids and chemical emulsifiers (22). 

Cyclic adenosine monophosphate-dependent protein kinase is useful for phosphorylation of a.a. residues in mild conditions. The modification makes the soybean proteins soluble in media rich in calcium and improves their emulsifying properties (Seguro and Motoki, 1990). 

There have been a limited number of studies on the effects of enzymic modification of protein concentrates on functional properties other than solubility. Studies on functional properties, as modified by enzymic treatments, emphasize foam formation and emulsifying characteristics of the hydrolysates. Treatment of chicken egg albumen alters the functional properties of the egg proteins in terms of foam volume and stability and the behavior of the proteins in angel food cakes (25). Various proteolytic enzymes were used to degrade the egg albumen partially. However, proteolytic enzyme inhibitors indigenous to the egg proteins repressed hydrolysis of the egg proteins compared with casein. 

The most important functional properties of proteins are solubility, water absorption and binding, rheology modification, emulsifying activity and emulsion stabilization, gel formation, foam formation and stabilization, and fat absorption [1-6]. They reflect the inherent properties of proteins as well as the manner of interaction with other components of the system under investigation. 

It is, therefore, clear that hydrophobic modifications of proteins can affect their ability both to form and to stabilize oil in water emulsions. Special care should be taken in using the proper combination of chain length and number of attached groups to the protein molecule in order to obtain good protein-based emulsifiers. 

---