Phenolic compounds of virgin olive oil: influence of paste preparation techniques

An experimental investigation was carried out on olive oils of the Ogliarola Salentina and Coratina cultivars to assess the influence of the two different olive grinding techniques and kneading process on the quality of the oils. The experimental data obtained showed that resistance to oxidation, total phenols and phenolic compounds analysed for HPLC were higher in the Coratina oils than in the Ogliarola oils. The use of hammer-crushers plus kneader rather than stone mills plus kneader always produced significant increases in the total phenols. Resistance to oxidation was assessed by the Rancimat method and showed a significant correlation with the amounts of total phenols and of an unidentified substance (peak I) which was conspicuously present amongst the substances evaluated for HPLC.