Phenolic compounds in natural black Spanish olive varieties

Abstract

There is increasing interest in olive phenolic compounds because of their biological properties as well as their contribution to the colour, taste and shelf life of olive products. Phenolic compounds in natural black Spanish olives are characterised by HPLC-UV and HPLC-MS. Hydroxytyrosol-4-β-D-glucoside has been identified as the major phenolic compound in natural black olives. A qualitative and quantitative study of phenolic substances such as hydroxytyrosol, salidroside, tyrosol, verbascoside, luteolin-7-glucoside, rutin, demethyloleuropein and oleuropein has been carried out. Traces of other phenolic compounds such as catechol, vanillic acid, apigenin-7-rutinoside and ligustroside have also been found by mass spectroscopy. Secoiridoid aglycons, the main phenolic compounds in olive oil, were not detected in olive flesh except the dialdehydic form of elenolic acid linked to hydroxytyrosol (HyEDA), particularly in the Arbequina olive variety and only traces were detected in other varieties. Among anthocyanins, cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside were the only anthocyanin compounds detected in all the varieties studied. The UV and MS spectra of several unknown phenolic compounds have also been described.