Proteins are essential to foods as they contribute greatly to the physical properties of foods through their ability to build or stabilize fibrillar structures, foams, emulsions, and gels (Belitz and others 2004). Furthermore, they are the precursors of aroma and color compounds that are formed during enzymatic or thermal reactions during production, processing or storage. Damodaran (1996) states that dietary proteins can be defined, for practical purposes, as those proteins that are easily digestible, non-toxic, 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 protein continues to grow, the food industry must look toward non-traditional protein sources. By understanding the functional, chemical and physical properties of food proteins, the industry may be able to find ways to provide proteins to the world's population. Dietary proteins are primarily made up of twenty common amino acids. Of these, there are eight amino acids essential 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 as either an acid or a base, and because they contain both an amino group and a carboxyl group, at approximately neutral pH, the molecule is a zwitterion (Damodaran 1996). Additionally, the...... middle of paper......, Ballard FJ, Copeland AD, DeSilva KJ, Dionysius DA, Francis GL, Goddard C, Grieve PA, McIntosh GH, Mitchell IR, Pearce RJ, Regsester GO. 1996. New opportunities from the isolation and utilization 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, California: Science Technology System. p 19.1-19.23.Lupo WJ. 1970. Soy Proteins: Their Functional, Chemical, and Physical Properties. J Agr Food Chemistry 18(6): 969-976.