Characterization of mono-varietal virgin olive oils obtained from Turkish National Germplasm Bank according to fatty acid composition, volatile profile, and sensory properties

Abstract

Mono-varietal virgin olive oils were obtained from Olea europaea L. olives grown in the National Olive Germplasm Bank in the same agronomic conditions for two harvesting years. Samples were characterized according to fatty acid composition, volatile profile, and sensory attributes, and varieties were compared using Pearson correlation, principal component analysis (PCA), and cluster analysis. Odor activity values (OAVs) of the volatiles were calculated to discuss relationships between individual sensory properties and volatiles. Although most of the samples overlapped on the score plots, some samples were located away from the others. The sample groupings on the dendrogram plotted using Ward's linkage were generally suitable with PCA results. Ethanol had a negative correlation with 9 out of 14 pleasant attributes. According to OAVs, trans-2-hexenal content had the most important effect on sensory attributes and positively correlated with flower odor, whereas hexenal content contributed to sweet attributes. Similarly, the effect of 1-hexanol content strengthened the flower attribute but weakened the bitter taste. These findings were also confirmed by separating some varieties rich in those volatiles on the PCA bi-plot of sensory attributes. Samples were grouped on a dendrogram in accordance with total ester and total C3, C5, and C6 acid contents.

Practical Application: Most olive production in Turkey is based on a few varieties, whereas 95 different endemic varieties were registered by Turkish National Germplasm Bank. This study provides information on the volatile composition, sensory profile, and fatty acid composition of virgin olive oils produced from some rare varieties with high oil content. Moreover, relationships and correlations between individual volatiles and sensory attributes were evaluated, and the main differences in fatty acid composition, volatile profile, and sensory attributes of these Turkish virgin olive oils and those produced from well-known varieties from major producing countries were compared. Thus, data on the main characteristics of extra virgin olive oils produced from Turkish olives were provided to the literature, these varieties were promoted internationally, and their cultivation was encouraged.