Proteins functional properties

High molecular weight and random coil structure of protein result in more associations and thereby enhance adhesive and cohesive properties. Although these characteristics are inherent in native gluten proteins, functional properties of other proteins may be improved by chemical or thermal processing. 

The expanded use of enzymes to modify protein functional properties has great promise for the food industry. Major advantages of using proteases compared to other agents include their specificity, their effectiveness at low concentrations and... 

The functionality of a protein is dictated by the molecular properties of the protein as modified by processing treatments, environmental factors, and interactions with other components. Environmental conditions, such as pH, ionic strength, type of salts, moisture content, and oxidation-reduction potential, may alter the functional properties of a protein in a food. Protein functional properties are also influenced by unit operations during processing... 

The literature is replete with methods to measure protein functional properties. For example, Kneifel et al. (1991) listed about 70 published methods to measure the water-holding ability of dairy proteins. Table B5.1.1, Table B5.1.2, and Table B5.1.3 list some common tests used to evaluate the functional properties of proteins. The methods in these tables should serve as examples only. Selection of the proper test to evaluate a particular functional property is difficult. A functional property test must meet the needs of the user and answer the question(s)... 

Rahma, E.H. and Abd El Aal, M.H. (1988) Chemical characterisation of peach nut oil an protein functional properties, in vitro digestibility and amino acids profile of flour. Food Chem., 28,31—43. Raie, M.Y. and Salma, S. (1985) Sesamum indicum and Papaver somniferum oils. Fette Seif Anstrichm., 87, 246-247. 

This selective review, which deals primarily with the chemical modification of soy proteins, is further limited to nondestructive chemical reactions which alter physical and biochemical properties of importance in food systems. Soy protein products have been modified by various chemical reactions including (a) treatment with alkalies and adds, (b) acylation, (c) alkylation and esterification, and (d) oxidation and reduction. In most instances these reactions have been applied to heterogeneous protein mixtures containing nonprotein impurities, and often to proteins of unknown prior history. Nonetheless, these reactions indicate that protein functional properties of value in food fabrication can be altered significantly through reaction with chemical reagents. It is recognized that chemically modified proteins must be critically evaluated for food safety. 

Egg white is composed of about 10% protein and 0.5% glucose. Maillard reaction of egg white proteins with glucose proceeds during the production of dried egg white powder, resulting in the formation of brownish pigments and the alteration of powdered protein functional properties such as solubility, emulsifying activity, gelling property (4). 

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