Milk and plant lipids influence the in vitro digestion of milk proteins

Infant formula is usually made from bovine milk but milk lipids are partly or fully replaced by plant lipids. However, little is known about the effect of lipid-protein interactions on their digestion. Therefore, this study examined how milk and plant lipids affect the in vitro digestion of milk proteins. Results show that emulsions of skim milk and milk lipids (SM-ML) had a similar particle size distribution and average particle size as emulsions of skim milk and plant lipids (SM-PL). During gastric digestion, caseins were digested faster in SM-ML compared to SM-PL and skim milk (SM). Intestinal milk protein digestion was slower in both SM-PL and SM-ML than SM, with SM-PL being the slowest. This could be caused by the difference in FFA composition and concentration, and in particular by the linoleic acid concentration. Together, we showed that in vitro milk protein digestion was differentially affected depending on lipid type.