International Journal of Food Science and Nutrition

Authors
Abdullah Abdo, Abdullrahman Al-Khalifa, Mohammed Ahmed, Qais Nogaim, Fouad Hassan, Chengnan Zhang

Abstract
This work sought to measure the contents of free, esterified, and bound phenolics (phenol and flavonoid) in peel and seed of two pumpkin varieties (sakaka and nagdi) and evaluate the antioxidant properties. The total phenol and flavonoid contents were evaluated using the Folin–Ciocalteu method, and the aluminum chloride colorimetric assay, respectively. The antioxidant activities of the two varieties were assessed using TEAC and reducing power assays. The free phenol content of nagdi peel was higher than that of sakaka peel and seed of two pumpkins, while esterified and bound phenol contents in nagdi seed were the highest among all samples examined. In the case of flavonoid content, the sakaka peel had the highest contents of free, esterified, and bound flavonoid. Combining the three fractions, the high contents of free, esterified and bound phenolics were found in nagdi peel. In the case of antioxidants properties, Free fraction from nagdi peel showed the highest antioxidant activity properties in both assays. Whereas, esterified fraction and bound fraction from nagdi seed and sakaka peel showed the highest TEAC and reducing power values, respectively. Generally, the Phenolics extracts of pumpkin by-products showed antioxidant properties. Therefore, these extracts could potentially in nutraceuticals preparation and functional food formulations.