Evaluation of antioxidant activity of watermelon peels (Citrullus lanatus L) and their application in cake making

Abstract

Watermelon peels (WP) were treated by ethanol 70% (v/v) to extract flavonoids and phenolic acids   then were identified by paper chromatographic technique. Synthetic antioxidant (butylated hydroxytoluene, BHT) and natural antioxidant (WPE) exhibited strong and close antioxidative activities (90.60% and 84.76%, respectively). The watermelon peels extract and BHT were added to sunflower oil at levels 100 and 200 ppm to keep its quality during heating at 180 ± 5°C for 28h. Moreover, the synthetic and natural antioxidants were added to cake made up by sunflower oil at the same levels. Cake was stored at refrigerator at 5°C for 28 days and the lipids were extracted every four days. The results reported that the addition of watermelon peels extract as natural antioxidant to sunflower oil and cake delayed the lipid peroxidation during heating oil and storage of cake.