Identification and quantification of trans fatty acids in bakery products by gas chromatography–mass spectrometry after focused microwave Soxhlet extraction

Trans fatty acids have been determined in fourteen bakery products using derivatisation by ester formation, gas chromatography–mass spectrometry for individual separation and identification/quantification following total fat isolation by Soxhlet extraction accelerated by focused microwave irradiation at the cartridge zone. The detection and quantification limits between 0.98 and 3.93 and 3.23–12.98 μg g⁻¹, respectively, and the linear dynamic ranges between LOQs values and 12,000 μg g⁻¹ thus obtained, demonstrated the utility of the approach for this type of analysis thanks to the wide determination range and high information level it provides. The proposed extraction method, which was validated by comparison with the Folch reference method – extraction under very mild conditions, shows that no changes of the original fat are produced under microwave-assisted extraction. The much shorter extraction time – 35 or 60 min vs. 3.5 h of the Folch method – and similar characteristics of the extract make this method an excellent alternative for the treatment of solid samples prior to trans fatty acids analysis. The target analytes were determined in fourteen bakery products; thus supporting the validity of the overall process.