Ultrasound-Assisted Extraction of Anthocyanins

To compare different solvents, the UAE technique was chosen given (i) the higher extraction yield of anthocyanin achieved in the optimization compared to PLE, (ii) the shortest extraction time (10 min for UAE and 13 min for PLE) and maintenance between two consecutive experiments (around 5 min for UAE and 1 h for PLE), and (iii) the lower solid-liquid ratio required (1:50 g/mL for UAE versus 1:13 g/mL for PLE). Here, the effect of the type of solvent on UAE yield and antioxidant activity was evaluated using the optimized conditions. The 1,2-alkanediol series (1,2-ethanediol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, and 1,2-hexanediol) and the glycerol ethers (1.0.1), (2.0.2), and (2.0.0) were selected in the following previous studies using these compounds [50 (link),51 (link)] and compared with the water and ethanol used as control solvents. The chemical structure of the solvents mentioned above is represented in Figure S5 in the Supplementary Materials. In addition to the anthocyanins yield, defined by HPLC-DAD quantification, the following analyses were conducted to evaluate the total phenolic content and antioxidant activity of the extracts recovered using different solvents.