Characterization of antioxidant olive oil biophenols by spectroscopic methods

BACKGROUND: Olive oil contains numerous phenolic components with well-recognized health-beneficial activity. The major phenolic compounds present in olives and virgin olive oil - hydroxytyrosol, oleuropein and the oleuropein aglycones 3,4-DHPEA-EA and 3,4-DHPEA-EDA - as well as some of their metabolites were studied in the present work, regarding their main structural preferences. Vibrational spectroscopy (Raman) coupled to theoretical methods were used, aiming at fully characterizing the systems and therefore enabling their quick and reliable identification in food samples. RESULTS: The Raman data, assisted by the theoretical simulations, allowed us to obtain the main geometrical and spectroscopic features of the olive oil constituents under study, which determine their known antioxidant and chemoprotective properties. In fact, it was verified that the spectra comprise distinctive bands for each compound, allowing their ready detection and differentiation. CONCLUSION: This is the first reported study on the structural behaviour of olive oil phenolic compounds, and it established Raman spectroscopy as a rapid, non-destructive and reliable analytical technique for identifying these bioactive components in dietary extracts. It can surpass other analytical methods currently used, once it allows the concomitant identification of several olive oil components in a particular sample. (C) 2010 Society of Chemical Industry