The size and interfacial composition of milk fat globules are key factors controlling triglycerides bioavailability in simulated human gastro-duodenal digestion

Lipids organisation might modulate fatty acid bioavailability leading to health implications. We determinedwhether the size and the interfacial composition of cow milk fat globules could affect triglyceridesdigestibility. Native fat globules of various sizes covered by their biological membrane (4.2 mm, large LFG6.6 mm, small SFG 1.7 mm) or homogenised heat-treated (0.3 mm) were digested in gastric and duodenalconditions simulating human physiology. Lipolysis extents were calculated from the amount of free fattyacids generated, and the fatty acid composition of the products of lipolysis was determined by GCanalysis. SFG were more efficiently hydrolysed than LFG by gastric (13.3 versus 5.6%), gastric pluspancreatic (62.9 versus 48.7%) and pancreatic (79.6 versus 54.7%) lipases. A higher lipid interface areawith native SFG, that might increase lipases binding sites, can explain these results. However, the homogenisation, which markedly decreases fat globule size increasing consequently the lipid/waterinterface area, did not improve gastric (9%) or duodenal (64.5%) lipolysis probably due to an importantchange in globule surface composition (proteins versus phospholipids). Interestingly, the size of the milkglobule (SFG and HM versus NM and LFG) controls the type of the free fatty acids generated by thehuman gastric lipase, palmitic versus oleic acid, suggesting a different orientation of the accessible mixedtriglycerides. Moreover, the type of monoglycerides produced from SFG digestion could be less atherogeniccompared to LFG. The size of fat globules governs gastric and duodenal lipolysis extent when thecomposition of the interfacial layer is appropriate. It might further control fatty acid bioavailabilityimpacting on gastric emptying rate via the preferential release of oleic acid, a strong stimulator of CCK