Evaluation of the potential of SPME-GC-MS and chemometrics to detect adulteration of ground roasted coffee with roasted barley

The objective of the present study was to verify the feasibility of detection of coffee adulteration with roasted barley by a comparative analysis of the volatile profiles of both coffee and barley, pure and mixed, at several roasting degrees. The methodology was based on a GC-MS analysis of the headspace volatiles of several samples of ground roasted coffee and barley. The collection and concentration of the headspaces was performed by solid phase micro-extraction (SPME). The separation of the non-adulterated and adulterated samples was accomplished by application of principal component analysis (PCA) to the chromatographic data obtained. It was observed that, the highest the degree of roast, the more easily discriminated were the adulterated samples, allowing for detection of adulterations with as low as 1% (w/w) roasted barley in dark roasted coffee samples.