Inhibition of lipolysis in bovine milk by proteose peptone

The ability of total milk proteose peptone and individual proteose peptone components to inhibit lipolysis in milk was examined. Proteose peptone (1.5 mg/ml) when added to milk inhibited lipolysis, and component 3 was a more effective inhibitor than component 5 or component 8-fast. Inhibition by proteose peptone also occurred when the milk was treated with between 2 and 20% v/v bovine blood serum or with 5 micrograms/ml heparin. In vitro activity of milk lipoprotein lipase and its stability were not affected by proteose peptone. It was concluded that proteose peptone does not interact with lipase or its activator and that the mechanism of inhibition involves the substrate.