Characterization of Four Alkyl-branched Fatty Acids as Methyl, Ethyl, Propyl, and Butyl Esters Using Gas Chromatography–Quadrupole Time of Flight Mass Spectrometry

Branched fatty chain fatty acids (BCFAs) are associated with the “mutton flavor” found with the aroma resulting from cooked older sheep meat with three BCFAs, 4-methyloctanoic (MOA), 4-ethyloctanoic (EOA) and 4-methylnonanoic (MNA) acids as the main compounds responsible for “mutton flavor”. Usually, BCFA analysis is done by gas chromatography (GC) with the use of quadrupole mass spectrometry (qMS) becoming predominant. 2-Butyloctanoic acid (2BO) has been used in this facility using as an internal standard to determine BCFA content in sheep fat. In this present work, GC-qMS, along with GC–quadrupole-time of flight MS (GC-QTOF-MS), have been deployed to characterize alkyl esters (as methyl, ethyl, propyl, and butyl) for MOA, EOA, MNA, and 2BO. This work presents, for the first time, the mass spectral characterization of 2BO for these alkyl esters using GC-qMS and GC-QTOF-MS.