Performance of whey protein hydrolysate–maltodextrin conjugates as emulsifiers in model infant formula emulsions

Model infant formula emulsions containing 15.5, 35.0 and 70.0 g L⁻¹ protein, soybean oil and maltodextrin (MD), respectively, were prepared. Emulsions were stabilised by whey protein hydrolysate (WPH) + CITREM (9 g L⁻¹), WPH + lecithin (9 g L⁻¹) or WPH conjugated with MD (WPH–MD). All emulsions had mono-modal oil droplet size distributions post-homogenisation with mean oil droplet diameters (D_4,3) of <1.0 μm. No changes in the D_4,3 were observed after heat treatment (95 °C, 15 min) of the emulsions. Accelerated storage (40 °C, 10 d) of unheated emulsions resulted in an increase in D_4,3 for CITREM (2.86 μm) and lecithin (5.36 μm) containing emulsions. Heated emulsions displayed better stability to accelerated storage with no increase in D_4,3 for CITREM and an increase in D_4,3 for lecithin (2.71 μm) containing emulsions. No increase in D_4,3 over storage was observed for unheated or heated WPH–MD emulsion, indicating its superior stability.