The present study investigates recovery of polyphenolic compounds from ripe mango (Mangifera indica L.) peel using deep eutectic solvents based on microwave-assisted extraction method. Lactic acid/sodium acetate/water (3:1:4) screened out from eight different types of deep eutectic solvent systems was used as extractant. A Box-Behnken design along with response surface methodology was applied to optimize the effect of microwave power (W), time (min), and liquid-to-solid ratio (mL g-1) on polyphenol extraction. The optimized conditions determined were power of 436.45 W, time of 19.66 min, and liquid-to-solid ratio of 59.82 mL g-1. Under the optimal conditions, the recovery of total phenolic content, ferric reducing antioxidant power, and 2,2-diphenyl-1-picrylhydrazyl scavenging activity was 56.17 mg gallic acid equivalent g-1 dw, 683.27 µmol ascorbic acid equivalent g-1 dw, and 82.64 DPPHsc%, respectively. High Performance Liquid Chromatography (HPLC) analysis revealed mangiferin as the prominent phenolic compound in the mango peel extracts. Microwave-assisted deep eutectic solvent extraction showed remarkable effects on the extraction efficiency of phenolic compounds as revealed from scanning electron microscopy analysis. Rancimat test results revealed that the oxidative stability almost doubled upon addition of purified mango peel extracts to the sunflower oil and thus paving way for the use of mango peel waste as a potential source of antioxidants.
Keywords: Antioxidant activity; Rancimat test; mango peel; microwave-assisted deep eutectic solvent extraction; polyphenolic compounds; response surface methodology.