Protein Thermal Stability

Proteins are organic polymers made up of chains of amino acids and are crucial material in many biological functions (Reece and others 2011). There are twenty basic amino acids, eight of which are essential to the adult human diet and must be consumed rather than synthesized inside the body. These essential amino acids are isoleucine, leucine, tryptophan, lysine, valine, phenylalanine, methionine, and threonine, with an added requirement of histidine in the diet of children (Potter and Hotchkiss 1995). Nonessential amino acids can be synthesized from these, and all amino acids are used as monomers to construct proteins which perform numerous important functions in the body (Reece and others 2011).

Most amino acids exist as isomers and are given a designation based on whether they rotate a plane of polarized light to the right or to the left, known as dextrorotatory “D” or levorotatory “L” isomers, respectively (Al-Holy and Rasco 2007). It should be noted that only L amino acids are used in protein synthesis (Weber and Miller 1981).

The biological functions of proteins include increasing the rate of biochemical reactions in the form of enzymes, moving important substances to where they are needed in the form of transport proteins, regulating the body in the form of hormones, allowing the body to move in the form of contractile proteins, and providing support in the form of structural proteins (Reece and others 2011).

In addition, proteins have a great deal of functionality in foods, including providing essential amino acids as well as energy, viscosity, texture, water holding capacity, foaming and emulsification properties, and allowing gel formation (Culbertson 2007). As mentioned above, essential amino acids provided by th...

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