Diversity for olive oil composition in a collection of varieties from the region of Valencia (Spain)

Abstract

Olive (Olea europaea) has a long history of cultivation in the Mediterranean region of Valencia (Spain) and many local varieties exist in the area. According to their economic importance, varieties are classified as National, Principal, Secondary, Local, Disseminate, and Minor. We have evaluated during four seasons the olive paste moisture content, fat content, and olive yield, and the olive oil acidity, peroxide index, K232 and K270 parameters, total phenolics, K225 parameter, and fatty acids content in 45 varieties from the Collection of Olive Varieties from the Region of Valencia. Considerable diversity existed among varieties for all traits studied, and the variety effect was much greater than the season effect. Wide ranges of variation have been found for most traits, with differences among varieties being of more than 10-fold for total phenolics. The coefficient of genetic variation and heritability values have been generally high, in particular for fatty acids content. A few varieties were found to present values outside the ranges established in the regulations for several olive oil composition traits, although in some cases, like a variety with above the limit content of oleic acid, they are of interest for breeding. Several correlations were found to be significant between the K232 index and fatty acids profile, in particular with oleic acid. The values obtained for variety averages as well as the principal components analysis show that economically relevant varieties present a lower diversity for composition than varieties with low economic importance. In this respect, selection among traditional materials can be of interest to recover neglected varieties with specific composition profiles, as well as to identify sources of variation for breeding programmes. Discriminant analysis allowed a correct classification of 99.4% of samples, showing that composition profiles, in particular fatty acids content, is a powerful tool for chemometry and fingerprinting of olive oil. Overall, the results show that the wide diversity found in the collection studied, in particular in the less economically important varieties, is of interest for the selection and breeding of olive varieties with improved quality.