IntroductionFoods are complex systems composed of different components, among which proteins play an important role in the structure, texture and stability of many foods (Hemar et al. 2001 ). Protein isolates and their concentrated products are commonly and widely used in the food industry, both for their added functionality and nutritional benefits. Ingredient functionality is important in the preparation, processing, storage, quality and sensory attributes of foods (Culbertson 2007). Besides these functions, proteins also increase solubility, water holding capacity, elasticity, gelation, emulsification and foaming (Smith 2003). Protein isolates typically contain around 90–95% protein, while protein concentrates contain around 65–70% protein (Thompson and Dinh 2010). Protein concentrates or isolates are added to foodstuffs lacking the inherent properties mentioned above (solubility, gelling, emulsification and foaming). These food products include: extruded foods, textured meat products, whipped toppings, and high-protein drinks (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 to obtain it. 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 how the protein folds and its three-dimensional (3D) appearance. Additionally, the quaternary structure, defined by the number of subunits and the formation of oligometric units, as well as the 3D structure are very important for the overall functionality of a protein concentrate or isolate (... ... middle of 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 protein concentration.Intl Dairy Day 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. Measuring functionality. Properties: Overview of protein functionality. In: Current Protocols in Food Analytical Chemistry. JR, Anon MC 1995. Effects of heat treatment of soy protein isolate on the characteristics and. structure-function relationship of soluble and insoluble J fractions from Agric and Food Chem. 43: 2471-2479.