Application of multivariate calibration and NIR spectroscopy for the quantification of methylxanthines in yerba mate (Ilex paraguariensis)

Yerba mate is native to subtropical forests and grows naturally in Brazil, Paraguay and Argentina. Its consumption has increased due to the health benefits attributed to the presence of phytochemical compounds, mainly methylxanthines, polyphenols and saponins. Methylxanthines have pharmacological properties such as stimulation of the central nervous system, peripheral vasoconstriction, relaxation of smooth muscle and stimulation of the myocardium. Near infrared (NIR) spectroscopy is a non-destructive method that provides rapid and simple analysis, facilitating the execution of quality control operations. The goal of the present study was to evaluate the use of near infrared spectroscopy, combined with multivariate calibration techniques, to predict the total methylxanthine content in yerba mate. Several multivariate calibration models were developed using PLS and evaluated by RMSECV and R2 values. The best model was developed using smoothing as pre-processing, the second derivative and MSC, starting from four latent variables (LV). This method presented R2 and RMSECV values of 0.924 and 0.2, respectively, with good predictive capability during external validation with a percent error of 7.5%. NIR analysis can be applied to predict the total methylxanthine content in yerba mate.