Proteins are essential to foods because they contribute greatly to the physical properties of foods through their ability to build or stabilize fibrillar structures, foams, emulsions and gels (Belitz et others 2004). In addition, they are the precursors of aromatic and coloring compounds that form during enzymatic or thermal reactions during production, processing or storage. Damodaran (1996) states that dietary proteins can be defined for practical purposes as proteins that are easily digestible, nontoxic, abundantly available, functionally usable in food products, and nutritionally adequate. As the world's population increases and the need to provide inexpensive but functional dietary proteins continues to grow, the food industry must turn to non-traditional protein sources. By understanding the functional, chemical and physical properties of food proteins, the industry can successfully find ways to provide protein to the world's population. Dietary proteins are mainly made up of twenty common amino acids. Of these, there are eight essential amino acids for adults and nine essential for children. Essential amino acids are those that the body cannot produce and therefore must be consumed by the individual. Each of the amino acids varies in chemical composition, net charge, chemical reactivity, hydrogen bonding potential, and solubility (Damodaran 1996). Physicochemical differences such as chemical reactivity, net charge, and solubility can also be found in the protein. Amino acids are amphoteric, meaning they can behave like an acid or a base and because they contain both an amine and a carboxyl group, at a pH close to neutral the molecule is a zwitterion (Damodaran 1996). Additionally, the...... middle of document......, Ballard FJ, Copeland AD, DeSilva KJ, Dionysius DA, Francis GL, Goddard C, Grieve PA, McIntosh GH, Mitchell IR, Pearce RJ, Regest GO. 1996. New opportunities arising from the isolation and use of whey proteins. J Dairy Sci 79:1454-1459.Swaisgood HE. 1996. Characteristics of milk. In: Fennema OR, editor. Food chemistry, 3rd ed. New York: Marcel Dekker, Inc. p 841-878. Thompson LD, Dinh T. 2009. Food Chemistry Laboratory Manual FDSC 4303/5305. Lubbock, TX: Texas Tech University, Department of Animal and Food Sciences. Walsh M, McMahon DD, Duncan SE. 2007. Milk and dairy products. In: Hui YH, editor. Food chemistry: principles and applications. West Sacramento, CA: Science and Technology System. p 19.1-19.23.Wolf WJ. 1970. Soy proteins: their functional, chemical and physical properties. J Agr Food Chem 18(6): 969-976.