59D-15 |
The binding of ionic surfactants to BSA and their impact on thermal stability and aggregation of BSA |
D. J. MCCLEMENTS and D. I. Kelley. Food Colloids and Bioploymer Lab, University of Massachusetts, Chenoweth Laboratory, Amherst, MA 01003 Globular proteins are used as functional ingredients in a variety of food products. Through interactions with surfactants, globular protein functionality can be altered in food products. These interactions may lead to changes in appearance, texture, and stability of gels, foams, and emulsions. The objective in this study, the interaction of cationic (DTAB) and anionic (SDS) surfactants with Bovine Serum Albumin (BSA) and the influence of these interactions on the thermal stability and aggregation of the protein were investigated. The influence of surfactants on the thermal denaturation of BSA in solution was measured using an ultrasensitive differential scanning calorimeter (DSC). An isothermal titration calorimeter (ITC) was used to measure the enthalpies of mixing, which characterized the binding of the surfactants to BSA in solution. Turbidity measurements were also used to characterize the influence of surfactants on the proteins in solution. The interaction of DTAB with BSA was endothermic at all surfactant concentrations (0-15mM). BSA was completely denatured when the DTAB concentration exceeded 4mM, and insoluble DTAB-BSA complexes were formed between 4mM and 10mM DTAB. The interaction of SDS with BSA was exothermic at low surfactant concentrations (below 1mM) and became endothermic at higher SDS concentrations (1-5mM). BSA became completely denatured when SDS concentrations exceeded about 4mM, and there was no evidence of an insoluble protein-surfactant complex at any SDS concentration. These results have important implications for understanding the influence of surfactants on globular protein functionality in foods. Food scientists can use this information to develope foods with improved quality.
Session 59D, Food Chemistry: Proteins and Physicochemical Properties
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