30C-21 |
The effect of cosolvent mixtures on the thermostability and gelation properties of Bovine Serum Albumin |
S. K. BAIER and D. J. McClements. Biopolymer and Colloids Laboratory, Dept. of Food Science, University of Massachusetts, 430 Chenoweth Laboratory, Amherst, MA 01003 JUSTIFCATION: The unfolding and aggregation of protein molecules determines many of the desirable attributes of food products, e.g. texture, stability, taste and appearance. Proteins are used in foods that contain a wide variety of different low molecular weight solutes, e.g. sugars and salts. The presence of these solutes can have a large impact on the molecular and functional characteristics of proteins and therefore it is important to systematically characterize their influence. OBJECTIVE: Our objective was to use a combination of calorimetric, rheological and spectroscopy techniques to systematically study the influence of different cosolvent mixtures on the thermal stability of a model globular protein (bovine serum albumin, BSA). METHOD: An ultrasensitive differential scanning calorimeter (DSC), UV-Visible spectrophotometer and shear rheometer were used to monitor the influence of cosolvent type (Glycerol, Sucrose, and Sorbitol), cosolvent mixtures and cosolvent concentration (0 - 40 wt%) on BSA unfolding, aggregation and gelation at temperatures from 25 to 90oC. The calorimeter provided information about the transition enthalpy (DH) and temperature (Tm), whereas the rheometer and spectrophotometer provided information about gelling and aggregation characteristics of the protein. RESULTS: The cosolvent system had a significant impact on the thermal transition temperature of the BSA. Glycerol, sorbitol and sucrose increased the thermal stability of the protein and promoted protein aggregation, which influenced both the appearance and rheology of protein gels. Our results are interpreted in terms of the preferential accumulation or exclusion of cosolvent molecules at the protein interface. SIGNIFICANCE: This study shows that by using a combination of modern analytical techniques it is possible to obtain fundamental knowledge about the influence of a cosolvent system on protein functionality. A better understanding of protein interactions with specific model cosolvent systems would enable food scientists to design and produce protein-containing foods with desirable organoleptic attributes and shelf life.
Session 30C, Food Chemistry: Proteins
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