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

Authors: LIANG, CHEN - Oak Ridge Institute For Science And Education (ORISE); Garcia, Rafael; Plumier, Benjamin; LEE, CHANGHOON - Oak Ridge Institute For Science And Education (ORISE); Huynh, Farah; Uknalis, Joseph

Submitted to: International Dairy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2023
Publication Date: 6/9/2023
Citation: Liang, C., Garcia, R.A., Plumier, B.M., Lee, C., Huynh, F.N., Uknalis, J. 2023. Proteolytic treatment of waste dairy ice cream to accelerate milk fat separation. International Dairy Journal. 145:105702. https://doi.org/10.1016/j.idairyj.2023.105702.
DOI: https://doi.org/10.1016/j.idairyj.2023.105702

Interpretive Summary: Ice cream manufacturers generate products that will not be sent to retailers for a variety of reasons such as product type changeover or packaging imperfections. These products are either used to feed animals or disposed via sewage or landfill. Being abundant in ice cream, butterfat is an economically and nutritionally valuable ingredient. It may be possible to recover the butterfat from waste ice cream and recycle it into the food supply as a quality ingredient. This study investigated the idea that treating waste ice cream with industrial enzymes would break down the protein and consequently release the butterfat to float to the surface. The researchers found that certain enzymes are particularly effective, requiring only a small dose and one hour of reaction time. Ice cream treated in this way does not release pure butterfat, but the treatment makes it much easier to recover the fat. The results of this study provide a very effective first stage for a waste ice cream butterfat recovery process.

Technical Abstract: Ice cream manufacturers generate products that will not be sent to retailers for a variety of reasons such as product type changeover or packaging imperfections. Butterfat may potentially be recovered as a valuable ingredient to be reapplied in human food processing. Fat aggregation and/or coalescence resulting in phase separation could happen spontaneously but very slowly in the ice cream emulsion. Adsorption of milk proteins on fat globule membranes hinders the aggregation and coalescence. In this study, commercially available proteases were chosen as treatments to disrupt the hindrance of milk proteins on fat destabilization. Two proteases were selected and tested on a variety of ice creams. Accelerated phase separation, faster creaming rate, and larger migrating particle size were observed with the protease treated ice cream emulsions. Investigation into the separation mechanisms showed that the two enzymes work differently; one may primarily promote fat aggregation by coagulating the milk proteins, and the other predominantly encouraged fat coalescence by removal of proteins from the fat globule membranes. These results provide a potential cost-effective solution for ice cream manufacturers to separate butterfat from waste ice cream, and shed light on how proteolytic treatments impact fat-in-water emulsion.