Effect of Steaming on Antioxidant Activity in Extracts of Ipomoea batatas Roots

Ipomoea batatas are one of the important plant sources in term of their nutritional content which known to have high antioxidant. A heat stable antioxidant is important to ensure their effectiveness for neutralize the free radical in human body. The purpose of this study is to determine the effect of steaming on antioxidant activity in Ipomoea batatas root extracts. Fresh root was steamed at 0, 10, 20, 30 and 40 minutes respectively. The steamed roots were extracted using ethanol. The antioxidant activity, total phenolic and flavonoid content of the extracts were determined by 2,2-diphenyl-1-picrylhydrazyl, Folin- ciocalteu and Aluminium chloride assay, respectively. All result show significant difference (p ≤ 0.05) except for DPPH assay. Antioxidant activity shows highest value at
30 min 17.561 ± 0.211 %, total phenolic shows highest value at 20 min 16.802 ± 0.676mg BHTE/g raw material and flavonoid shows highest value at 10 min 27.861 ± 0.621mg QE/g raw material. It can be conclude that steaming increase the antioxidant activity however further increase of steaming time may destroyed antioxidant in the samples extracts.