Thermally induced aggregation of whey proteins : characterization of protein isolates and beta-lactoglobulin/ pectin interactions
Kazmierski, Michelle Nicole
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Despite its widespread utilization, information relating to the characterization of commercially available whey protein isolate (WPI) is limited. Further insight into its behavior in mixed systems can enhance its use as a “value-added” ingredient. The thermal aggregation behavior of WPI was examined, as well as interactions between -lactoglobulin, the main functional protein in whey, with a high methoxyl and a pectinesterase-modified pectin at low pH, and stability of orange juice with added whey protein. Molecular weight averages and distribution of WPI aggregates varied significantly with temperature and concentration. Upon heating 10% WPI solutions, native protein decreased with increasing temperature and hydrodynamic diameters increased with temperature. Protein composition of the aggregates did not change upon heating. Pectin charge distribution affected the formation of soluble complexes with -lactoglobulin. Fortification was most stable upon addition of -lactoglobulin and WPI at pH 3.0 and a heat treatment of 85°C.