Quantification of adulterants in mezcal by means of FT-MIR and FT-NIR spectroscopy coupled to multivariate analysis

Mezcal is an alcoholic beverage with a high commercial value and is often adulterated to obtain economical profit, however, adulteration is an illegal practice that can damage consumer's health. FT-MIR and FT-NIR spectroscopy along with multivariate analysis were used to quantify adulterants (water, ethanol, methanol) in three mezcal classes (white, rested, aged). Calibration models were constructed using principal component regression (PCR), partial least squares with single y-variable (PLS1) and partial least squares with multiple y-variables (PLS2) algorithms. The PLS2 showed the best predictive results for FT-MIR (R-2 = 0.9579-0.9895); and PLS1 for FT-NIR (R-2 = 0.9401-0.9665). The predictions of models were compared to gas chromatography with flame ionization detector (GC-FID) and no significant difference was found (p <= 0.05). Results show that the authenticity of mezcal can be verified through FT-MIR and FT-NIR spectroscopy coupled to multivariate analysis because it is reliable and fast (as compared to GC-FID).