Antioxidative effects of Brassica juncea and Moringa oliefera prepared by different processing methods

The effects of different cooking methods (boiling, microwave cooking, frying and steaming ) on the antioxidant activity of Brassica juncea (BJ) and Moringa oliefera (MO) were assessed by measuring the total phenolic contents (TPC), total flavonoid content (TFC), DPPH radical scavenging activity and Fe(2+)-chelating ability . TPC (mg gallic acid equivalents per 100 g of dry weight) and TFC (quercetin equivalents per gram of extract) of the fresh, boiled, microwaved, fried and steamed BJ were found to be 23.16, 27.7, 18.7, 35.94, 22.06 and 27.09, 27.8, 24.5, 36.34, 18.01 respectively. For MO it was found to be 34.6, 31.5, 31.6, 39.4, 33.72 and 70.84, 58.13, 55.4, 69.5, 52.78. A proportionate variation in DPPH radical scavenging activity and Fe(2+)-chelating ability was observed. The results of the present investigation showed that all the cooking methods affected the antioxidant properties of the vegetables; however, frying exhibited less deleterious effects when compared with those of other treatments. Thus an appropriate method might be sought for the processing of such vegetables to retain their antioxidant components at maximum level.