Antioxidant Effect of Citrus Peel Extract on Oxidation Control of Canola Oil

The aim of this work was to evaluate the effects of extracts of different citrus fruits peel on the oxidation of canola oil during 5-day accelerated condition and compare the antioxidant activity of the peel extracts from citrus fruits (cultivated in north and south of Iran).The citrus peel ethanolic extracts prepared by ultrasound-assisted technique (150 w, 40 ◦C, and 30 min) showed significantly higher extraction efficiency and phenolic compounds in comparison to the extracts produced through the conventional extraction method. Southern Bitter orange peels had the highest amount of TPC (1.78 mg GAE/g) followed by northern bitter orange (1.46 mg GAE/g), southern lemon (1.25 mg GAE/g), northern lemon (1.02 mg GAE/g), southern orange (1.32 mg GAE/g), and northern orange (1.10 mg GAE/g)peels. TPCs of citrus peels of the south of Iran were higher than TPCs of north-cultivated citrus fruits. The oxidative stability and the free radical scavenging(DPPH) activity of southern bitter orange peel extract was the highest among the other treatments followed by northern bitter orange, southern orange, northern orange, southern lemon, and northern lemon extracts. According to the results, the peel extracts containing phenolic compounds as natural antioxidants have the potential of reacting with the free radicals produced from lipid oxidation.