A comparative study of the composition of triacylglycerol molecular species in equine and human milks

The composition of triacylglycerols (TAGs) is a very useful parameter to understand several properties of creams and anhydrous milk fat products such as nutritional value, technological applications, and textural properties. In this paper, the molecular species of TAGs of equine milk were identified using a combination of non-aqueous reversed phase high-performance liquid chromatography, electrospray ionization mass spectrometry and high temperature gas chromatography and were then compared to the TAGs composition of human milk. The data showed that equine milk contained a complex mixture of different TAGs molecular species resulting from the widest range of its fatty acids as compared to human milk. In particular, the largest differences in TAGs composition between equine and human milk concerned TAGs containing medium-chain fatty acids; for C-8, C-10, and C-12. In terms of carbon number (CN), TAGs with CN36-CN46 were the most abundant in equine milk with a maximum concentration at CN44 (15.3%), while TAGs with CN44-CN52 were the predominant in human milk with a maximum of CN52 (30%). For both milks studied, the experimentally determined distributions of TAGs molecular species deviated from those predicted by the random hypothesis. TAGs with CN44 corresponding to a fatty acids carbon number distribution of C-8/C-18/C-18, C-12/C-14/C-18, and C-10/C-16/C-18 were apparently preferentially synthesized in equine milk. Whereas, in human milk, mixed TAGs with CN52 containing C-16/C-18/C-18 fatty acids were much higher than would be expected from the random calculation.