Influence of lecithin on the processing stability of model whey protein hydrolysate-based infant formula emulsions

Whey protein hydrolysate (WPH)-based oil-in-water (O/W) emulsions containing lecithin (0-5%, w/w, oil) were produced and stored at 4 °C for 14 days. Surface tension and interfacial tension of these systems were measured for formulation development. Fat globule size distribution (FGSD) analysis and confocal laser scanning microscopy (CLSM) were used to assess the physical stability of emulsions during storage and identify mechanisms of instability. Lecithin decreased interfacial tension between oil and aqueous phases of model emulsions and allowed formation of smaller oil droplets on homogenisation. However, low-intermediate levels (1-3%) of lecithin caused coalescence and shift to bimodal FGSD during storage of emulsions.