Identification and quantification of phenolic compounds in fresh and processed table olives of cv. ‘Kalamata’

Abstract

Mediterranean diet is almost synonymous to the healthy lifestyle and diet nowadays. Some of the major components of the diet are the products of the olive tree, fruits and olive oil, which are classified as medical foods, due to their nutraceutical benefits and their protective properties against cancer, cardiovascular diseases, age-related diseases, neurodegenerative disorders and other diseases. The key contributors to these properties are the phenolic compounds such as hydroxytyrosol, tyrosol and oleuropein. Table olives are being processed with several methods in order to reduce the bitterness of the olive fruit and the impact of the processing on phenolic compounds has not been studied extensively. In the present study, changes in the concentration of the most important phenolic compounds were quantified in fresh, Greek-style and Spanish-style processed olive fruits of cv. ‘Kalamata’, using two different analytical methods for identification and quantification: high-performance liquid chromatography diode array detector (HPLC-DAD) and ultrahigh-performance liquid chromatography tandem mass spectrometry (LC-(ESI)-MS/MS). The phenolic compounds that were identified and quantified were hydroxytyrosol, tyrosol, verbascocide, rutin, oleuropein and luteolin. Both processing methods used altered the phenolic compounds concentration in ‘Kalamata’ olive fruits compared to untreated fruits. In both analytical methods, a statistically significant increase in verbascoside and hydroxytyrosol concentration and a statistically significant decrease in rutin concentration was observed in both, Greek-style and Spanish-style, processed olive fruits.