DPPH-scavenging capacity of chloroplastic pigments and phenolic compounds of olive fruits (cv. Arbequina) during ripening

This work studies the antioxidant capacity of chloroplastic pigments (chlorophylls and carotenoids) and phenolic compounds during the growth and ripening of olive fruits Olea europaea L. cv. Arbequina, grown under organic and conventional methods. Chloroplastic pigments are lipophilic compounds, while polyphenols are hydrophilic. The antioxidant capacity of lipophilic and hydrophilic fractions was measured by scavenging of the 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH). The lipophilic fraction comprised an acetone solution (containing chlorophylls and xanthophylls) and a hexane solution (including β-carotene), while the hydrophilic fraction corresponded to a methanol solution (containing total phenolic compounds). During the development and ripening phases of fruits, both chloroplastic pigments and total phenolic compounds followed a parallel pattern. Both fractions presented the highest antioxidant capacity during the first weeks of the fruit growing, coinciding with the highest chloroplastic pigments and total phenolic compounds contents. There was a high correlation between the antioxidant capacity of the hydrophilic fraction and total phenolic compounds. The antioxidant capacity of the acetone extract was also positively correlated with the total chlorophyll and xanthophyll content, while lower correlation between the β-carotene content and the antioxidant capacity of the hexane extract was found. All the parameters studied in organic and conventional fruits followed similar evolution patterns, with slight differences.