A comparative study between the antioxidant properties of peel (flavedo and albedo) and juice of some
commercially grown citrus fruit (Rutaceae), grapefruit (Citrus paradisi), lemon (Citrus limon), lime (Citrus
aurantiifolia) and sweet orange (Citrus sinensis) was performed. Different in vitro assays were applied to
the volatile and polar fractions of peels and to crude and polar fraction of juices: 2,2-diphenyl-1-picrylhydrazyl
(DPPH) radical scavenging capacity, reducing power and inhibition of lipid peroxidation
using b-carotene–linoleate model system in liposomes and thiobarbituric acid reactive substances
(TBARS) assay in brain homogenates. Reducing sugars and phenolics were the main antioxidant compounds
found in all the extracts. Peels polar fractions revealed the highest contents in phenolics, flavonoids,
ascorbic acid, carotenoids and reducing sugars, which certainly contribute to the highest
antioxidant potential found in these fractions. Peels volatile fractions were clearly separated using discriminant
analysis, which is in agreement with their lowest antioxidant potential.
