Classification of Coffee Beans by GC-C-IRMS, GC-MS, and 1H-NMR
Score plots of PLS-DA for classification by country of origin (Colombia versus Others) performed with GC-MS (2 LVs, (a)) and 1H-NMR (8 LVs, (b)). Red, green, and blue open circles are for Colombia, Peru, and Brazil, respectively. (c) VIP plots obtained for GC-MS model. (d) NMR spectra colored according to the results of VIP analysis. The red color (VIP > 1) means that the variable contributes to prediction, while the light blue color (VIP < 1) is for predictors that do not contribute. VIP scores obtained from NMR show that most of the spectra (peaks) are contributing to the classification, highlighting that a large number of observable compounds are important for the determination of origin of coffee beans. A total of 662 predictors were found with VIP > 1.