Wednesday, January 22, 2020

Protein Thermal Stability Essay -- Scientific Research, Food Industry

In the food industry, plant-derived protein, such as soy protein, is being used as an economical replacement for animal-derived proteins, such as whey and casein, but limitations occur due to the functionality and stability of these proteins in different applications (Pasupuleti and Demain 2010). Protein concentrates contain 50-80% protein, while protein isolates contain greater than 90% protein (Hui 2007). Soy protein isolates are utilized in bakery goods to add texture and emulsification properties with minimal change to the color and flavor of the food (Riaz 1999). In addition, the combination of soy protein concentrates and dried whey protein is used in bakery products as an economical replacement for milk (Riaz 1999). Whey and casein, while typically found in milk, can be isolated and utilized in many other applications, such as the branded ingredient Simplesse, a fat replacer (Hui 2007). Simplesse employs microparticulation, during which milk proteins are denatured and folded i nto smaller proteins that mimic the lubricating nature of lipids (Hui 2007). The isoelectric pH range for soy protein, during which solubility is minimal and precipitation may occur due to hydrophobic interactions, is between 4.2 to 4.6 (Pabby 2009). The isoelectric pH range for casein is 4.5 to 4.7 (Pabby 2009). After casein precipitates, the remaining supernatant contains the whey proteins, which may be removed through a process called salting-out (Mine and Shahidi 2006). Ammonium sulfate added to the supernatant will dissociate and the ions will interact with the water to alter water’s structure and increase surface tension, leading to the decreased solubility of and precipitation of nonpolar molecules, such as whey proteins (Mine and Shahidi 2006... ...rk: Springer Science + Business Media. 229 p. Poklar N, Vesnaver G. 2000. Thermal denaturation of proteins studied by UV spectroscopy. J Chem Edu 77(3):380-2. Riaz MN. 1999. Healthy baking with soy ingredients. Cereal Food World. 44 (3):136. Ryan M, McEvoy E, Duignan S, Crowley C, Fenelon M, O’Callaghan DM, FitzGerald RJ. 2008. Thermal stability of soy protein isolate and hydrolysate ingredients. J Food Chem 108(2):503-10. Thermo Fisher Scientific Inc. 2011. Protein assay data analysis. Rockford, Ill.: Thermo Fisher Scientific Inc. Available from: 5056-8A76-4ED7-480BC9A5AD92. Accessed Nov 20, 2011. Thompson LD, Dinh T. 2009. Food proteins – protein isolation and thermal stability. FDSC 4303/5305 food chemistry laboratory manual. Lubbock, Tx.: Texas Tech University, Department of Animal and Food Sciences.

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