Effect of mono- and diglycerides on physical properties and stability of a protein-stabilised oil-in-water emulsion

Mono- and diglycerides (MDGs) are emulsifiers used to modify physical properties and creaming stability in protein-stabilised emulsions. This study aims to understand the effect of different MDGs and sodium stearate on oil droplet size and creaming stability of emulsions. Model emulsions with eight MDG compositions and a control (protein only) were prepared by microfluidisation. Emulsion droplets and creaming stability were characterised by droplet size, zeta potential, viscosity and creaming index during aging (28 days at 25 °C). Emulsions containing 0.2% MDGs produced 15-30% smaller oil droplets and 17-27% lower polydispersity indices compared to the control. Sodium stearate (6% of MDGs) increased zeta potential by 12.6-17.3 mV in emulsions containing saturated MDGs and 1.8-5.0 mV in unsaturated MDGs. Unsaturated MDGs showed better creaming stability than the control after 28 days of aging with no improvement observed for saturated MDGs. Unsaturated MDGs are promising emulsifiers to improve creaming stability of protein-stabilised emulsions.