Anthocyanins extraction from Amazonian matrices using natural deep eutectic solvents: characterization and ecological...

This study investigated the effectiveness of natural deep eutectic solvents (NADES) as a green alternative to traditional organic solvents for the extraction of anthocyanins from three Amazonian matrices: açaí, mangosteen pericarp, and purple yam. High-intensity ultrasound-assisted extraction (HIUS) was evaluated by varying key processing parameters such as molar ratio, solid-to-liquid ratio (S/L), added water, extraction time, and ultrasound power. Results showed that both molar ratio and added water had a significant impact on extraction efficiency. The addition of water to NADES was crucial in reducing viscosity and enhancing anthocyanin solubility, thereby improving mass transfer. However, excessive water led to decreased extraction yields, likely due to the disruption of hydrogen bonds within the NADES system. The extraction time and ultrasound power proved to be critical factors, as prolonged extraction periods and high power resulted in the degradation of anthocyanins. This study concluded that NADES yielded promising results for anthocyanin extraction. The optimal anthocyanin extraction conditions for açaí (132.20 mg/100 g) were a 1:2 molar ratio, 1:120 S/L, 30% added water, 5 min extraction, and 600 W power. For mangosteen pericarp, the optimal anthocyanin extraction conditions (58.81 mg/100 g) were a 1:2 molar ratio, 1:120 S/L, 30% added water, 5 min, and 1200 W power. For purple yam, the optimal anthocyanin extraction conditions (25.95 mg/100 g) were a 1:3 molar ratio, 1:120 S/L, 20% added water, 5 min, and 1200 W power. Additionally, the NADES-extracted anthocyanins demonstrated good stability across a range of pH values. Liquid chromatography coupled with electrospray ionization and tandem mass spectrometry (LC-ESI-MS/MS) analysis revealed variability in phenolic profiles, while açaí and mangosteen pericarp showed diverse bioactive compounds, including isorhamnetin and epicatechin. Purple yam exhibited no detectable phenolics. Compared to conventional solvents, NADES extraction exhibited a lower environmental impact, as assessed by Ecoscale and Analytical GREEnness Metric (AGREE) tools.