Characterization of Brazilian coffee based on isotope ratio mass spectrometry (δ¹³C, δ¹⁸O, δ²H, and δ¹⁵N) and supervised chemometrics

Authentication of ground coffee has become an important issue because of fraudulent activities in the sector. In the current work, sixty-seven Brazilian coffees produced in different geographical origins using organic (ORG, n = 25) and conventional (CONV, n = 42) systems were analyzed for their stable isotope ratios (δ¹³C, δ¹⁸O, δ²H, and δ¹⁵N). Data were analyzed by inferential analysis to compare the factors whereas linear discriminant analysis (LDA), k-nearest neighbors (k-NN), and support vector machines (SVM) were used to classify the coffees based on their origin. ORG and CONV cultivated coffees could not be differentiated according to C stable isotope ratio (δ¹³C; p = 0.204), but ORG coffees presented higher values of the N stable isotope ratio (δ¹⁵N; p = 0.0006). k-NN presented the best classification results for both ORG and CONV coffees (87% and 67%, respectively). SVM correctly classified coffees produced in São Paulo (75% accuracy), while LDA correctly classified 71% of coffees produced in Minas Gerais.