Ion Mobility–Mass Spectrometry Approach for the Comparison of Sheep and Goat Milk Lipidomes

In this work, we report an analytical procedure to investigate the lipid compositions of sheep and goat milk. This approach is based on an ion mobility-high-resolution mass spectrometric method to facilitate the identification of complex lipid species and their regiochemistry. A common triacylglycerol profile was observed for sheep and goat milk samples, while a higher abundance of medium-chain fatty acids was observed at the sn-2 position for sheep milk. Furthermore, differences can be also observed in the levels of saturated and unsaturated fatty acids at the sn-2 position. In terms of lipid classes, goat milk showed higher levels of triacylglycerols, phosphatidylinositols and ether-linked phosphatidylethanolamines, while sheep milk showed higher levels of free fatty acids, lysophosphatidylethanolamines, lysophosphocholines and non-hydroxy fatty acid-dihydrosphingosine ceramides when compared with goat milk.