Efficient extraction of anthocyanins from red onion (Allium cepa L.) using natural deep eutectic solvents. 
A. González-De-Peredo, A. Maroto, A. Memboeuf, Food Analytical Methods 2026, 19, 152, DOI: 10.1007/s12161-026-03061-4

In onions, anthocyanins, together with flavonols such as quercetin, represent some of the most abundant phenolic compounds. Although anthocyanins typically account for around 10% of the total flavonoid content, they play a key role in enhancing the nutritional and functional properties of pigmented varieties. In line with the growing interest in sustainable extraction methods, this study investigates the use of natural deep eutectic solvents (NaDES) as environmentally friendly extractants for the recovery of anthocyanins from red onion samples. NaDES, composed of choline chloride, acting as a hydrogen bond acceptor, and different hydrogen bond donors (levulinic acid, urea, tartaric acid, and 1,3-propanediol) were evaluated. The mixture of choline chloride and levulinic acid (1:3 molar ratio) showed the highest extraction efficiency. A Box–Behnken design coupled with multiresponse optimization was employed to determine the optimal extraction conditions for five target anthocyanins: cyanidin 3-glucoside, delphinidin-3,5-diglucoside, cyanidin 3-(6″-malonyl-glucoside), cyanidin 3-laminaribioside, and cyanidin 3-(6″-malonyl-laminaribioside). The optimal parameters were an extraction time of 17.5 min, a water content of 65% in NaDES, and a temperature of 20.5 °C. The developed method showed good repeatability and intermediate precision (CV < 10%). In comparison with methanol as a traditional nongreen extraction solvent, NaDES provided comparable or even higher recoveries, particularly for delphinidin-3,5-diglucoside and cyanidin 3-O-(6″-malonyl-laminaribioside), highlighting its potential as a promising green alternative for anthocyanin extraction.