Ultrasound-Assisted Extraction of Anthocyanins from Haskap (Lonicera caerulea L.) Berries Using a Deep Eutectic Solvent (DES)

Research background. Haskap berries are one of the richest natural sources of anthocyanins and their extracts can be used for nutraceuticals and functional food ingredients. Deep eutectic solvents (DES) comprising food-grade or generally recognized as safe (GRAS) components show promise as natural solvents, but have not been applied to haskap berries. Thus, the aim of this study is to investigate the extraction of anthocyanins from haskap berries using a DES consisting of citric acid and D-(+)-maltose. Experimental approach. The experimental approach used ultrasound-assisted extraction with a DES consisting of citric acid and D-(+)-maltose as the solvent to achieve a sustainable green extraction process. Response surface methodology (RSM) with a Box-Behnken experimental design was used to study the effect of varying the extraction temperature, time of extraction, V(solvent)/m(sample) ratio (mL/g) and the water volume fraction (%) in the DES on the total anthocyanin content (TAC) in the haskap berry extracts. Results and conclusions. Under the optimal extraction conditions (75 degrees C, 10 min, 50.4 mL/g and 90 % water), a predicted TAC extraction on dry mass basis yielded 21.2 mg/g, with experimental error of 7.2 %. The TAC yield and anthocyanin profiles were similar to those obtained with conventional organic solvents. Novelty and scientific contribution. This is the first study investigating the use of a food-grade DES comprising GRAS components for the extraction of anthocyanins from haskap berries. These results indicate that the studied DES (citric acid and D-(+)-maltose) is a suitable alternative solvent for extracting anthocyanins for food-grade applications.