From drupes to olive oil: How do bioactives variate during a single production procedure?

It has been well established, that the beneficial effects of virgin olive oil (VOO) are related to its content in polyphenols and secoiridoid derivatives. Several factors, such as fruit variety, ripening stage, malaxation time, temperature etc, have been mentioned to play key role in the quality of the final product and literature data are contradictory. In the present study we monitored the qualitative and quantitative alterations of numerous bioactive polyphenols and secoiridoids, throughout VOO production from a rich in polyphenols olive variety Koroneiki, at a two-phase oil mill in Greece. The compounds were monitored, with the application of LC-DAD-ESI(-)-HRMS (LTQ-Orbitrap) platform, out of the four main steps of the production procedure: drupes, olive paste, first oil, final refined oil. All initial materials were obtained simultaneously, during a single production line and were similarly extracted with methanol, after de-fatting. The extracts were finally enriched through Diol SPE cartridges before the LC injections. The chemical profiles of extracts, pure compounds and internal standards, were monitored in full scan mode and by ion extraction, in a post-acquisition analysis. Results showed an significant increase in the dialdehydic derivatives, oleacin and oleocanthal from drupes to the oil with a simultaneous decrease in oleuropein and ligstroside, which were absent from the final product. Hydroxytyrosol content was also increased but a great quantity seems to be lost during the final oil refinement processing.