Background: The digestion fate of milk fat depending on its supramolecular structure for a given dairy product composition has rarely been studied.
Aim of the study: To highlight differences of lipid digestion, we measured (i) the plasma triacylglycerol and cholesterol concentrations and (ii) the total plasma fatty acid profile of fasted rats force-fed with different dairy preparations; the three creams and the unemulsified preparation had a similar composition with different and controlled fat suprastructures.
Methods: All preparations, manufactured in the laboratory from a given milk batch, contained 205 +/- 3 g . kg(-1) fat that was either fed (i) unemulsified consecutively to the skim milk phase, or as a cream with the following fat globule structures: (ii) native milk fat globules of approximately 4 microm covered with the native milk fat globule membrane (MFGM), (iii) small native milk fat globules of approximately 2 microm selected from the latter by microfiltration and covered by the MFGM, or (iv) fine homogenized fat droplets of approximately 1 microm covered mainly with caseins.
Results: The plasma triacylglycerol appearance was delayed for the creams compared with the rapid onset for the unemulsified preparation. At 90 and 180 min after feeding, the plasma triacylglycerol enrichment was significantly lower for the homogenized cream than for the unemulsified preparation. At 120 min after feeding, triacylglycerol enrichment was significantly lower for each cream than for the unemulsified preparation. At 180 min after feeding, the plasma relative enrichment in C12, C14, C15, C16 and C18:1 n-9 fatty acids was significantly lower for the homogenized cream than for unemulsified fat and regular cream.
Conclusions: Global lipid digestion based on plasma triacylglycerol enrichment and relative enrichments in some fatty acids was decreased with small homogenized milk fat droplets compared to unemulsified milk fat. These data show that dairy products with the same composition but varying in fat supramolecular structure result in different kinetics of lipid digestion, which could be of health concern.