Fatty Acid Profiles of Virgin Olive Oils from the Five Olive-Growing Zones of Extremadura (Spain)

In this study, 278 samples of virgin olive oil from 40 mills belonging to five olive-growing zones of Extremadura were evaluated according to their fatty acid composition. An analysis of variance of the fatty acid contents, and their principal group subtotals and ratios revealed significant differences at the 95 % confidence level between zones. Means were compared using Tukey’s HSD test (p < 0.05). A discriminant analysis, taking the zone as the grouping variable and the different fatty acids and their ratios as independent variables, explained nearly 90 % of the variance with the first two functions. The model correctly classified 88.8 % of the analysed samples into their proper olive-growing zone. Validation against an extra test set of 30 samples resulted in 90 % being correctly classified; the results of the discriminant analysis were therefore considered to be validated. A two-dimensional graphical representation of the different groups studied using the first two resulting canonical discriminant functions clearly showed the Sierra Norte of Caceres and Vegas del Guadiana each to be clearly separated from the rest and from each other, while the other three zones—Siberia, Serena and Tierra de Barros—overlapped considerably.