Stability against heat-induced aggregation of emulsions prepared with a dry-heated soy protein isolate-dextran mixture

The effect of heating in boiling water, of oil-in-water emulsions stabilized with an incubated at 60 degrees C dry soy protein isolate (SPI)-dextran mixture, was studied. Droplet aggregation and floc formation was not detected after heating for time periods of up to 30 min, while the opposite was observed for emulsions prepared with the non-incubated SPI-dextran mixture, which exhibited extensive floc formation even after heating at 100 degrees C for a few seconds. The results are explained in terms of SPI-dextran hybrid formation, following incubation of the mixture at 60 degrees C, which when absorbs at the emulsion droplet surfaces inhibits droplet-protein aggregate interaction and floc formation. The data for the apparent mean droplet size increase with time of the heat aggregated emulsions stabilized with the non-incubated mixture as well as those for SPI in the absence of dextran are analyzed to determine the kinetics of the aggregation process. (c) 2005 Elsevier Ltd. All rights reserved.