Concentration of 4-methoxy-2-methyl-2-butanethiol in Spanish virgin olive oils

The sensitivity of a stable isotope dilution assay for 4-methoxy-2-methyl-2-butanethiol (MMB) causing the blackcurrant-like odour in olive oils was improved. After spiking the oil sample with labelled MMB, the thiols were separated from the volatile fraction with an immobilized reagent for thiols. MMB and its standard were purified by multi-dimensional gas chromatography of the thiol fraction and determined by mass spectrometry. The new procedure was applied to three Spanish oils differing in the intensity of their blackcurrant-like odour note. The concentrations of MMB lay between 0.4 μg kg−1 and 4.3 μg kg−1.