Abstract

PHENOLIC CONTENTS AND ANTIOXIDANT ACTIVITY OF PEELS AND SEEDS OF ORANGE (CITRUS SINENSIS) CULTIVATED IN IRAQ

Abdul-Lateef Molan*, Massar Hadi Ismail and Riyadh Hameed Nsaif

ABSTRACT

Four different extracts of Iraqi sweet orange (Citrus sinensis) peels and seeds were evaluated for their total phenolic content (TPC) using the Folin–Ciocalteu method. In addition, the scavenging activity against the DPPH radical was evaluated by the DPPH method. The results showed the presence of phenolic compounds in peels and seeds with varying proportions. The TPC of the peels were significantly (P < 0.05) higher than that of the seeds. The highest TPC and radical scavenging activities were found in both peels and seeds prepared in 5% hydrochloric acid (HCl) solvent, followed by those prepared in boiling water, 50% ethanol and then cold water. The antioxidant activity found in the peels and seeds of Citrus sinensis, should be attributed to the presence of phenolic compounds as evidenced by the positive correlation between the radical scavenging activity and TPC. In conclusion, citrus by-products (peels and seeds) possess relatively high antioxidant activity and may represent very rich sources of natural low-cost antioxidants which can be used for various purposes. Moreover, the results of the present study recommend using diluted solution (5%) of HCl for optimum extraction of phenolic compounds and consequently high antioxidant activity.

Keywords: Orange (Citrus sinensis), Phenolic contents, Antioxidant activity, Peels, seeds.