IntroductionFoods are complex systems composed of different components, among which proteins play an important role in the structure, consistency and stability of many foods (Hemar and others 2001). Protein isolates and their concentrated products are commonly and widely used in the food industry for both their additional functionality and their nutritional contributions. The functionality of ingredients is important in the preparation, processing, preservation, quality, and sensory attributes of foods (Culbertson 2007). In addition to these functions, proteins also increase solubility, water-holding capacity, elasticity, gelation, emulsification, and foaming (Smith 2003). Protein isolates generally contain approximately 90–95% protein, while protein concentrates contain approximately 65–70% protein (Thompson and Dinh 2010). Protein concentrates or isolates are added to food products that lack the intrinsic properties mentioned above (solubility, gelation, emulsification and foaming). Such food products include: extruded foods, textured meat products, whipped toppings, and protein-rich beverages (Kinsella, 1994). The use of a protein concentrate or isolate in a food source depends on its functional properties which are influenced by the biochemical nature of the protein and the extraction and purification method used for its derivation. The structure of the protein is of extreme importance in its ability to function in the food system. The amino acid sequence of a protein determines the protein's folding and three-dimensional (3D) appearance. Furthermore, the quaternary structure, defined by the number of subunits and the formation of oligometric units, together with the 3D structure is very important for the overall functionality of a protein concentrate or isolates (...... middle of the paper... . ..Protein Structure and Molecular Enzymology 1547(2): 339-350.Schokker EP, Singh H. Pinder DN, Creamer LK 2000. Heat-induced aggregation of β-lactoglobulin AB at pH 2.5 influenced by ionic strength and proteins concentration.Intl Dairy Jour 10(12): 233-240.Singh R, Singh G, Chanhan GS 2000. Nutritional evaluation of soy-enriched biscuits JFood Sci Tech 37: 162-164.Smith DM 2003. Measurement of functional properties: overview of protein functionality testing. Current protocols in analytical food chemistry. Harkins EW, ed. John Sorgentini DA, Wagner JR, Anon MC 1995. Effects of protein isolate heat treatment. of soy on the characteristics and structure-function relationship of the soluble and insoluble fractions. J of Agric and Food Chem 43: 2471-2479.