n this paper (open access) the authors used of solid-phase microextraction (SPME)-gas chromatography-time-of-flight mass spectrometry (GC/Q-ToF-MS) combined with chemometrics to detect key differences between adulterated and non-adulterated ground roast coffee. They drilled into these differences and found two potential chemical markers for common adulterants.
They compared the aroma profiles of ground roasted coffee with some commonly used adulterants (ground roasted barley, corn and soybean). The SPME fibre collected and concentrated the headspace volatiles. Non-adulterated and adulterated samples were distinguished after applying some chemometric tools (principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and hierarchical cluster analysis (HCA)) on the obtained chromatographic data. Two volatile compounds (1H-imidazole-4-methanol and benzene-2-(1,3-butadienyl)-1,3,5-trimethyl) were identified as potential markers for the determination of adulterants (ground roasted barley, corn or soybean) in ground roasted coffee (p-value cut-off<0.001 and fold change (FC) cut-off>10). Also, 2-furanmethanol and 2-formyl-1-methylprrrole were found as marker candidates for roasted coffee powder.
The authors tested this approach and were able to detect selected herbal adulterants (5% w/w) found in ground coffee.
