Phenolic compounds and antioxidant activity of the apple flesh and peel of eleven cultivars grown in Brazil

The total phenolic, flavanol, monomeric anthocyanin contents and the antioxidant activity of flesh and peel of 11 apple cultivars from Brazil were investigated. Concentrations of the parameters measured differed significantly among the apple cultivars and were highest in the peel compared to the flesh. Total phenolic content (mg GAE/100 g fresh matter) ranged from 128.3 (Golden Delicious) to 212.0 (Epagri-F5P283) in the flesh and 304.6 (Golden Delicious) to 712.6 (Catarina) in the peel. Total flavanol content (mg CAE/100 g fm) varied from 11.7 (Epagri-SJ11) to 28.2 (Epagri-F43P23) and from 32.4 (Epagri-SJ11) to 147.7 (Catarina) in the flesh and peel, respectively. COOP-24 peel had the highest total anthocyanin content. The Epagri-F5P283 and Epagri-F43P23 flesh and Catarina peel had the highest antioxidant activity while Golden Delicious flesh and peel had the lowest. The total phenolic content and antioxidant activity were significantly correlated in both flesh (R2 = 0.717) and peel (R2 = 0.716). The contribution of phenolics to the antioxidant activity in peel suggests that their removal may induce a significant loss of antioxidants.

Research highlights
► Phenolic compounds varied considerably among apple cultivars.
► Apple peels had highest phenolic content and antioxidant activity.
► Phenolic content contributes significantly to the antioxidant activity of apples.