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 determined whether the size and the interfacial composition of cow milk fat globules could affect triglycerides digestibility. Native fat globules of various sizes covered by their biological membrane (4.2 μm, large LFG 6.6 μm, small SFG 1.7 μm) or homogenised ± heat-treated (0.3 μm) were digested in gastric and duodenal conditions simulating human physiology. Lipolysis extents were calculated from the amount of free fatty acids generated, and the fatty acid composition of the products of lipolysis was determined by GC analysis. SFG were more efficiently hydrolysed than LFG by gastric (13.3 versus 5.6%), gastric plus pancreatic (62.9 versus 48.7%) and pancreatic (79.6 versus 54.7%) lipases. A higher lipid interface area with 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/water interface area, did not improve gastric (9%) or duodenal (64.5%) lipolysis probably due to an important change in globule surface composition (proteins versus phospholipids). Interestingly, the size of the milk globule (SFG and HM versus NM and LFG) controls the type of the free fatty acids generated by the human gastric lipase, palmitic versus oleic acid, suggesting a different orientation of the accessible mixed triglycerides. Moreover, the type of monoglycerides produced from SFG digestion could be less atherogenic compared to LFG. The size of fat globules governs gastric and duodenal lipolysis extent when the composition of the interfacial layer is appropriate. It might further control fatty acid bioavailability impacting on gastric emptying rate via the preferential release of oleic acid, a strong stimulator of CCK.