Design and process optimisation of double emulsions loaded with casein hydrolysate

Water-in-oil-in-water (W1/O/W2) emulsions show promise for encapsulating hydrophilic active substances. However, the low stability of W1/O/W2 hinders its use for encapsulation purposes, and peptide encapsulation has challenges due to its surface-active properties. This study aimed to determine the appropriate formulation based on turbidity and encapsulation efficiency, as well as the optimal production parameters (ultrasound amplitude and time) for double emulsions containing casein hydrolysate, with a focus on the second homogenisation stage. Double emulsions were produced with three different emulsifiers (polysorbates 20, 60, or 80) at different concentrations (0.25%, 1%, or 1.75%) and dispersed phase ratios (10%, 20%, or 30%) using an ultrasound homogeniser. The results indicated that dispersed phase ratios and emulsifier concentrations had higher impact on emulsion properties than emulsifier types. A stable emulsion with high encapsulation efficiency was achieved with 1% polysorbate 20 and a 30% dispersed phase ratio, using sonication at 54% amplitude for 66 s.