Effect of the interplay between lipid phase properties and ethanol concentration on the stability of model cream liqueurs

Cream liqueur formulations are limited to ethanol concentrations below 20 wt% due to clumping of the lipid phase at higher levels. However, it is not generally understood whether the properties of the dispersed phase, containing surface-active and crystallising lipids, or the detrimental impact of ethanol on the emulsifying properties of protein are responsible for this limitation. Here, model cream liqueurs were processed, containing solely ethanol (0, 15 or 50 wt%), water, sodium caseinate (3 wt%) and one of three lipid phases (10 wt%): sunflower oil stripped off surface-active molecules, native sunflower oil, or clarified butterfat. Ethanol was added either before or immediately after emulsion processing in a microfluidizer, and final emulsions were stored at 5 °C. At 0 and 15 wt% ethanol, independent of point of ethanol addition, native oil and butterfat resulted in up to three times smaller emulsion droplets than treated oil, remained stable for at least nine months. The presence of ethanol (15 wt%) suppressed butterfat crystallisation at the selected storage temperature. At 50 wt% ethanol, the presence of a crystallising lipid fraction negatively affected emulsion stability, as such butterfat emulsions showed immediate clustering and creaming. Native oil-based emulsions were stable against creaming and coalescence at this ethanol level. The study concludes that the interplay of ethanol-compromised emulsifying properties of the protein and the crystallisation characteristics of the lipid inhibits the formulation of a commercially viable cream liqueur at elevated ethanol concentrations. For non-crystallising lipid phases however, the novel findings reported in this study are encouraging in view to formulating alternative product ranges.