Time- and temperature-dependent changes in the adsorbed layer on caseinate-stabilized emulsion droplets

Changes in composition of the adsorbed layer in sodium caseinate emulsions stored at different temperatures have been observed. These changes are, in part, dependent on the oil droplet phase (milk-fat or soybean oil). At storage temperatures below 15 degreesC the milk-fat emulsion adsorbed layer exhibits a decrease in surface coverage as a result of casein molecule desorption. This was not observed for soybean oil emulsions. Above 15 degreesC storage temperatures there is a time-dependent and temperature-dependent polymerization of casein molecules in both milk-fat and soybean oil emulsion droplet adsorbed layers. At temperatures below 15 degreesC these changes are explained in terms of the different solid-fat contents of milk-fat and soybean oil. Above 15 degreesC it is hypothesized that chemical changes in the adsorbed layer are taking place. (C) 2001 Elsevier Science Ltd. All rights reserved.