Effect of Cooking Treatments on Drying Kinetics, Polyphenols Content and Antioxidant Activity of Orange-Fleshed Sweet Potato

Abstract

This study examines the effects of boiling, steaming, and microwaving on the drying kinetics, total polyphenol content (TPC), antioxidant activity, and total carotenoid content (TCC) of orange-fleshed sweet potatoes (OFSP), a vital source of beta-carotene for combating vitamin A deficiency. Results indicate that steaming preserved the highest TPC at 4.28 mg GAE/g DW, while microwaving yielded the highest TCC at 527.35 µg BCE/g DW. Antioxidant activity, measured via DPPH radical scavenging, was significantly enhanced by steaming (3.48 μmol TE/g DW) and microwaving (3.29 μmol TE/g DW) compared to boiling (1.40 μmol TE/g DW). The drying kinetics followed the Page model, demonstrating a strong fit (R² > 0.9988) across treatments, highlighting the complex moisture loss behaviors influenced by cooking methods. Boiling resulted in a 51% reduction in TPC due to leaching, while both steaming and microwaving significantly increased antioxidant activity despite some degradation of phenolic compounds during microwaving. These findings underscore the importance of cooking methods in optimizing the nutritional value of OFSP, providing practical recommendations for food preparation to enhance health benefits and address vitamin A deficiency in vulnerable populations.