PHENOLIC-COMPOUNDS IN VIRGIN OLIVE OILS - FRACTIONATION BY SOLID-PHASE EXTRACTION AND ANTIOXIDANT ACTIVITY ASSESSMENT

The polar fraction of virgin olive oil was separated into two main par ts (A and B) using solid phase extraction. Analysis of individual comp onents by RP-HPLC indicated that the part (A) contained only simple ph enols and phenolic acids. Part (B) had a complex nature. The two parts tested for their antioxidant activity showed relatively high protecti on factors in safflower oil stored at 80 degrees C. Part B was found t o contribute more than part A to the stability of the oil. The antioxi dant activity of both fractions was related to their content of total polyphenols and o-diphenols. Acidic and alkaline hydrolysis showed sig nificant quantitative changes in the HPLC profiles indicating the pres ence of ether and ester bonds while high-performance anion exchange ch romatography of sugars after hydrolysis gave evidence for the presence of only traces of glycosides. A first attempt to identify a character istic chromatographic peak of part B by HPLC fractionation and mass sp ectrometry showed the presence of an ester of tyrosol most probably wi th a dicarboxylic acid.