SPME/GC/Q-ToF-MS and Chemometric Approaches for Detecting Adulteration in Ground Roasted Coffee

In the world, adulteration of coffee might have been observed for years owing to dishonest food manufacturers. Today, various analytical methods have been used for food fraud detection. In the current research, the potential use of solid-phase microextraction (SPME)-gas chromatography-time-of-flight mass spectrometry (GC/Q-ToF-MS) combined with chemometrics was evaluated to detect coffee adulteration. The aroma profiles of ground roasted coffee were compared with some commonly used adulterants (ground roasted barley, corn and soybean). The SPME fiber assembly DVB/CAR/PDMS was utilized to collect and concentrate the headspace volatiles of ground roasted coffees and adulterants, and the volatile profile analyses were performed by GC/Q-ToF-MS. Non-adulterated and adulterated samples were accomplishedly separated 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. This analytical method allowed the detection of selected herbal adulterants (5% w/w) found in ground coffee. Key words: Coffee adulteration; volatile profiles; SPME; GC/Q-ToF-MS; chemometrics.