Phenolic composition of olive fruit and virgin olive oil: distribution in the constitutive parts of fruit and evolution during the oil mechanical extraction process.

Phenolic compounds in peel, pulp and seed of olive fruits, their distribution in oil and by-products produced during mechanical oil extraction and the endogenous enzymes that can catalyse phenolic modifications during processing were studied. All the constitutive parts of the fruit contained secoiridoids and phenyl-acids, while luteolin-7-glucoside and rutin were found only in the peel. Crushing led to a strong decrease of secoiridoid glucoside and increase in aglycone derivatives. Verbascoside contnet did not vary significantly. A significant amount of paste phenols (>96%) was found in by-products; oil did not contain either secoiridoid glycosides or verbascoside but showed high concentrations of secoiridoid aglycones. Malaxation reduced phenol concentration in oil and in by-products. High levels of glycosidase and oxidoreductase activities were observed in pulp and seeds.