One-step characterization of triacylglycerols from animal fat by MALDI-TOF MS.

Comparative characterization of milk fat, lard, and beef tallow triacylglycerols (TAG) has been achieved by using matrix-assisted laser desorption/ionization–time-of-flight (MALDI-TOF) mass spectrometry (MS). The samples formed characteristic patterns, with major TAG signals differing in quantity and intensity according to the fat. In milk fat, the significant contribution of short-chain fatty acids (C4–C10) extends the TAG number to the C20–C60 range. In lard and beef tallow, C12–C18 fatty acids restrict the range to C48–C54, also typical of vegetable oils. Fats originating from ruminants contain odd TAG missing in lard. Signature TAG were identified for each animal fat. C20–C46 specifically fingerprint milk fat; 52:5, 54:5 and 54:6 TAG mark lard; and 55:0, 55:1, 55:2 and 54:0 TAG typify beef tallow. Fats were also analyzed after hydrogenation or bromination; hydrogenation helped to fingerprint the low-abundant long-chain TAG and to distinguish short-chain native TAG from collision-induced fragments; bromination allowed clear separation of saturated and unsaturated TAG. Differences in the fatty acid composition amongst homologous isobaric TAG of different structures were identified by post-source decay analysis of hydrogenated precursors. MALDI-TOF has provenadvantageous for simultaneously detecting TAG at various unsaturation degrees within different TAG classes (Cn). The data provide insight into animal fat differentiation on a molecular basis, increasing the analytical description to a new level, proving the so far underestimated capacity of MALDI-TOF MS in this field.