The effect of using orange peel (Citrus Sinensis) as a biosorbent on the quality properties and heavy metal content of cold-pressed sesame oil

Nowadays, due to the disadvantages of the conventional methods of removing heavy metals, application of agricultural waste and by-products from food processing as a biosorbent has been considered. This study investigates the effect of orange peel concentration and agitation time on the quality characteristics and the level of heavy metals (Pb, Fe, Cu, Cd and As) in cold-pressed sesame oil. Results showed that the concentration of orange peel and agitation time significantly affected the quality characteristics and the level of heavy metals (p< 0.05). Compared to the control sample, the values ​​of conjugated diene, conjugated triene, peroxide value, free fatty acids and chlorophyll of samples containing 6 g/l of orange peel decreased by 68.10, 50.66, 49.61, and 15.1, 44 and 65.76%, respectively. But carotenoid and total polyphenol contents increased by 8.03% and 37.30%, respectively. Also, conjugated diene, conjugated triene, peroxide value, free fatty acids and carotenoid decreased up to 30 minutes, chlorophyll decreased up to 45 minutes, and total polyphenol increased up to 45 minutes of agitation. Comparing with control sample, the content of lead, iron, copper, arsenic and cadmium in the oil sample containing 6 g/liter orange peel, decreased by 24.31, 43.49, 47.16, 36.49 and 21.53% respectively. Increasing agitation time up to 60 minutes, decreased the level of Pb, Fe, Cu, As and Cd by 35.87, 50.65, 56.12, 47.81 and 21.50%, respectively. The results showed that orange peel as a biosorbent can improve quality, reduce heavy metals in oil and create added value.