Proteolytic treatment of waste dairy ice cream to accelerate milk fat separation

Waste products are generated within the ice cream manufacturing process for a variety of reasons. Milk fat may potentially be recovered as a valuable ingredient to be reapplied in the human food chain. In this study, Flavourzyme and Formea CTL (chymotrypsin-like protease) were selected and tested on a variety of melted ice creams to destabilize the emulsion and facilitate fat separation. With 1% (w/w) enzyme/protein dose and 1 h reaction at 50 °C, 20–60% of the original emulsion weight was segregated as serum under mild centrifugation. Faster creaming velocity, larger migrating particle size, and decreased continuous phase viscosity were found to contribute to the accelerated separation. Flavourzyme promoted fat flocculation by coagulating milk proteins adsorbed at the fat surface, and chymotrypsin encouraged fat coalescence by removal of the adsorbed proteins from the fat surface. This study provides an efficient first step to recover milk fat from waste ice creams.