Enhancement of coalescence by xanthan addition to oil-in-water emulsions formed with extensively hydrolysed whey proteins

The objective of this study was to examine the effects of added xanthan gum on the formation and properties of emulsions (4 wt% corn oil) formed with a highly hydrolysed commercial whey protein (WPH) product under a range of conditions. Stable oil-in-water emulsions could be formed using 4 wt% WPH and hydroxylated lecithin as emulsifiers. Addition of xanthan to these emulsions above a certain critical concentration caused flocculation of the oil droplets, by depletion mechanisms, which resulted in a marked increase in the creaming rate. Interestingly, this depletion flocculation also promoted the coalescence of droplets during storage of the emulsions for up to 1 week at room temperature. The rate of coalescence was enhanced considerably with increasing concentration of xanthan in the emulsion up to 0.12%. At higher levels of xanthan addition, the rate of coalescence decreased gradually, apparently because of the high viscosity of the aqueous phase.