Quantification of 2-Methyl-3-furanthiol, 2-Furfurylthiol, 3-Mercapto-2-pentanone, and 2-Mercapto-3-pentanone in Heated Meat

A stable isotope dilution assay was developed for quantification of the potent odorants 2-methyl-3-furanthiol (MFT), 2-furfurylthiol (FFT), 2-mercapto-3-pentanone (2M3P), and 3-mercapto-2-pentanone (3M2P) in heated meat. The volatiles of meat were extracted with dichloromethane, which was spiked with definite amounts of stable isotopomers of MFT, FFT, and 3M2P. The analytes and their labeled standards were enriched by reaction with p-hydroxymercuribenzoic acid, and after liberation, the thiols were assayed by dynamic headspace gas chromatography in combination with mass spectrometry. The following amounts (micrograms per kilogram) were found in meat samples boiled for 45 min: (beef) MFT, 7−28, FFT, 13−42, 3M2P, 55−73, 2M3P, 20−44; (pork) MFT, 6−9, FFT, 8−10, 3M2P, 66−117, 2M3P, 11−14; (lamb) MFT, 5−11, FFT, 9−14, 3M2P, 30, 2M3P, 10. Chicken contained per kilogram 4.5 μg of MFT, 2.4 μg of FFT, 100 μg of 3M2P, and 13 μg of 2M3P after a boiling period of 60 min. Keywords: Isotope dilution assay; 2-methyl-3-furanthiol; 2-furfurylthiol; 3-mercapto-2-pentanone; 2-mercapto-3-pentanone; beef; chicken; pork; lamb; flavor