Lab-on-a-fruit: an approach for chemical evaluation of olive oil composition prior to extraction.

Three chemical families (fatty acids, phenols, and volatiles) can be used to differentiate virgin olive oil (VOO) based on its health benefits, organoleptic features, and oxidative stability. We propose a lab-on-a-fruit approach to characterize these families in olives, providing qualitative and quantitative information on VOO composition prior to extraction. We developed a 100% accurate model to predict the predominant secoiridoids in VOO by measuring oleacein, oleuropein, oleuropein glucoside, and ligstroside aglycone in fruits. Significant correlations (p-value<0.05, r > 0.5) were found between volatiles in fruits and oils, which are associated with "green" and "ripen" fruitiness in VOOs. Lastly, no differences were found in the content of predominant FAs, palmitic and oleic acid; in contrast, linoleic acid content was significantly lower in VOOs than in fruits due to its role as a substrate in the lipoxygenase pathway, which is activated during VOO extraction and promotes the formation of volatiles responsible for fruitiness attributes.