The Sterol and Erythrodiol + Uvaol Content of Virgin Olive Oils Produced in Five Olive-Growing Zones of Extremadura (Spain)

The content of sterols and erythrodiol + uvaol was studied in 273 virgin olive oil samples from 40 mills in five olive-growing zones of Extremadura (Spain). An analysis of variance showed significant differences at a confidence level of 95 % between the different zones in each of the main sterols and in the sum of erythrodiol + uvaol. The results of a linear discriminant analysis, considering the different olive-growing areas as categorical dependent variables and the different sterols as independent variables, explained 78.2 % of the variance with the first two discriminant functions. The resulting model correctly classified 86.9 % of the samples analysed. A validation study was conducted to verify the goodness of the discriminant analysis, resulting in 79.3 % of the new samples used for validation being correctly classified. In the graphical representation of the different groups studied considering the proposed model’s first two discriminant functions, the centroids of the Sierra Norte de Caceres, Vegas del Guadiana and Tierra de Barros olive-growing zones were clearly separated, but this was not the case for the other two zones—La Serena and La Siberia.