Characterisation and optimisation of physical and oxidative stability of structured lipid-based infant formula emulsion: Effects of emulsifiers and biopolymer thickeners

Response surface methodology (RSM) was applied to investigate the effects of lecithin (0-0.4 g/100 ml), monoacylglycerol (0-0.4 g/100 ml), locust bean gum (LBG; 0-0.1 g/100 ml), and carrageenan (0-0.02 g/100 ml) on the physical and oxidative properties of structured lipid-based infant formula emulsion containing dairy proteins, lactose, vitamins, minerals and other micronutrients. Particle size, optical stability, viscosity, relative content of docosahexaenoic acid, stearidonic acid and total oxidation value were assessed during 28-day storage. ANOVA results showed that the experimental data were satisfactorily fitted to second-order polynomial models by multiple linear regression. The contour plots illustrated that lecithin and monoacylglycerol played a dominant role in controlling the emulsion stability compared to LBG and carrageenan. Lecithin content significantly affected all the responses measured, particularly lipid oxidation. Increasing monoacylglycerol concentration led to an increase in particle size and emulsion viscosity. The optimal condition to achieve the highest stability was predicted to be 0.2, 0.4, 0.045, and 0.015 g/100 ml lecithin, monoacylglycerol, LBG and carrageenan, respectively. The verification data further demonstrated the suitability of the models explored by RSM. Overall, the findings obtained in this study have important implications for the successful incorporation of structured lipid into infant formula emulsion for better infant nutrition and health.