Determination of geographic origin of agricultural products by multivariate analysis of trace element composition

Abstract

Samples of orange juice, pistachio and macadamia nuts were analysed for selected elements using inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry. Discriminant analysis was used to form mathematical models for predicting the geographic origins. The accuracy of these models was assessed using re-substitution and cross-validation analysis, for the orange juice and macadamia nut samples, and by the calibration set–prediction set method for the pistachio nut samples. Perfect prediction results were achieved for the pistachio nut samples. Re-substitution analysis results for the orange juice and macadamia nut samples indicated prediction accuracies of 96 and 98%, respectively, while cross-validation results indicated 88 and 78%, respectively. Separations were visualized by performing canonical discriminant analysis involving the same elements as in the discriminant analysis, and plotting canonical scores for the first two or three canonical functions. Complete resolution of all samples by geographic origin was achieved for all three commodities.