Optimization of anthocyanin extraction from mango peel wastes using ultrasound and microwave-assisted natural deep eutectic solvents

This study investigates the efficient extraction of anthocyanin from mango peel wastes using ultrasound and microwave-assisted hydrophilic natural deep eutectic solvents (NADES). Among the various NADES combinations tested, choline chloride: lactic acid (1:2) exhibited the highest extraction yield. Process variables such as sonication duration (15–30 min), microwave intensity (30.11–60.22 W/g), and microwave duration (20–60 s) were optimized using the Box–Behnken experimental design. Under optimized conditions, the anthocyanin yield significantly increased to 44.77 mg/g dry weight for ChCl: lactic acid, compared to 4 ± 0.02 mg/g dry weight for acidified ethanol, demonstrating the synergistic effect of ultrasound and microwave-assisted NADES in enhancing extraction efficiency. Spectrophotometric and stability analyses confirmed the integrity and storage behavior of the extracted anthocyanin under different environmental conditions. Additionally, antioxidant activity (DPPH) and ferric reducing power of the ChCl: lactic acid extract were recorded as 39 ± 0.1 and 40 ± 0.82 μmol AAE/g dry weight, respectively, which were markedly higher than those obtained using the conventional method (17.11 ± 0.16 and 20.29 ± 0.87 μmol AAE/g dry weight). The total phenolic content was higher in ChCl: lactic acid (2.82 ± 0.72 mg GAE/g dry weight) than in acidified ethanol (1.21 ± 0.17 mg GAE/g dry weight). Color analysis also showed greater color intensity for ChCl: lactic acid (1.211 ± 0.23) compared to acidified ethanol (1.093 ± 0.10). The findings support the use of green solvents and non-conventional extraction techniques for the valorization of agro-industrial waste into valuable bioactive compounds.