Effect of the fat globule membrane on in vitro digestion of milk fat globules with pancreatic lipase

The rate and extent of in vitro lipid digestion in raw and recombined milk were investigated by determining the release of fatty acids in simulated intestinal fluid containing pancreatic lipase. Changes in the globule size, surface charge and microstructure of fat globules during digestion were examined. In the absence of bile extract, the rate of lipid digestion was slower in raw milk than in recombined milk, suggesting that the composition of the milk fat globule membrane influences the rate of lipid hydrolysis in milk. Flocculation of fat globules occurred in the early stages of digestion; the globules then coalesced to form large particles, from within which triacylglycerols were removed. However, in the presence of bile extract, the changes in the size and microstructure of the fat globules during digestion were different. Bile extract may therefore affect physicochemical interactions of fat globules and hence alter the lipolysis during the digestion.