Citrus residues: A potential source of phenolics with high antioxidant values
This work explores underutilized Lemon (Citrus limon) and Galgal (Citrus pseudolimon) residues for their phenolic contents and in-vitro antioxidant activities. Methanolic extracts from different parts of these two Citrus species were tested for total phenolic contents (TPC), total flavonoid contents (TFC), DPPH radical scavenging activity, % inhibition of linoleic acid peroxidation and reducing power by using respective in-vitro antioxidant model assays. The percentage yield of extracts, total phenolic and flavonoid contents among parts tested varied from 6.13 – 24.20 g/100g, 98.20 – 199.18 (mg gallic acid equivalent/g of extract) and 19.95 – 39.60 (mg catechin equivalent/g of extract), respectively. Percent inhibition of linoleic acid peroxidation and DPPH radical scavenging capacity for the tested extracts ranged between 3160 and 40-62%, respectively. The overall order of antioxidant potential among parts of Citrus species was established to be: C. pseudolimon leave > C. limon leave > C. pseudolimon peel > C. limon peel > C. pseudolimon seed ≈ C. limon seed. It could be concluded that extracts of Citrus fruit residues, especially, leaves can be explored as an economically viable source of natural antioxidants and nutraceuticals.