Multivariate characterization of table olives according to their mineral nutrient composition

Different commercial presentations of table olives were characterized by their mineral compositions. Cu, Fe, Mn, Zn, Ca, Mg, Na, K, and P were determined. The processing of table olives affects the mineral content of commercial presentations and significant differences (p < 0.05) were found among green (Spanish style), directly brined, and ripe olives. A predictive discriminate analysis showed that the most discriminating elements were Fe, K, Na, Mn, Cu, and P (among styles) and with Ca (among cultivars). A good classification and cross-validation was observed in the case of elaboration styles but discrimination among cultivars was less conclusive. A further analysis of the confusion matrix, according to cultivars, showed that the lower classification efficiency, in this case, was mainly due to misclassification of samples from Manzanilla and Gordal cultivars. The analysis of the confusion matrix can be useful when the assessment of its results is not obvious.