RESUMO

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.

Assuntos

Café/química , Análise de Alimentos/métodos , Espectrometria de Massas/métodos , Brasil , Isótopos de Carbono/análise , Deutério/análise , Análise Discriminante , Análise de Alimentos/estatística & dados numéricos , Espectrometria de Massas/estatística & dados numéricos , Isótopos de Nitrogênio/análise , Agricultura Orgânica , Isótopos de Oxigênio/análise , Máquina de Vetores de Suporte