Purpose: The aim of this work was to investigate the potential of Headspace Solid Phase Microextraction - Gas Chromatography Mass Spectrometry (HS/SPME-GC/MS) and e-nose in the detection of the fraudulent addition of horse adulterants to minced beef.
Methods: Portions of minced beef and horse were mixed to obtain five ratio mixtures corresponding to 0%, 10%, 20%, 40%, and 100% horse in beef. Afterwards, six different burgers (75-80g), for each level of adulteration (30 samples in total), were analyzed using both HS/SPME-GC/MS and a 12 MOS e-nose system. This procedure was repeated three times, in order to take into account the variablity between batches.
Results: Meat volatilome for the two species exhibited qualitative, as well as quantitative differences. As far as the GC/MS chromatograms are concerned, they were analyzed with untargeted and targeted approaches. Principal component analysis for both instruments showed that the increasing amount of horse adulteration in beef followed a distinct gradient pattern. Supervised data analysis results following orthogonal-PLS-DA gave very good discrimination between pure and adulterated samples, yielding 88.1% and 94.3%, overall, correct classification for GC/MS and e-nose data, respectively. Random forest (RF) classifier managed to increase the accuracy by 1.7% for both chemometric methods. Qualitatively, dimethyl sulphide, methyl acetate, acetoin, diacetyl, pentanal, and 2,3-octane-dione were positively correlated with beef meat, while γ-butyrolactone, 3-hepten-2-one, cis-4-heptenal, ethyl alcohol, butyric and hexanoic acid were considered important for horse meat.
Significance: This study demonstrates the potential of GC/MS and e-nose in the rapid detection of meat adulteration. Furthermore, it showed the superiority of e-nose to GC/MS.