Resumen
As a nonthermal process, ultrasonic extraction was optimized to obtain 13.21 mg/g of highly bioactive but extremely heat-sensitive cyanidin-3-O-galactoside (C3G) from Aronia melanocarpa Elliot under the following conditions; 75 kHz input frequency, 18.8 °C for the temperature, and 6.0 h process time. This yield was higher than 10.01 mg/g from a conventional juice extraction and was also higher than those from other reported sources. This concentration was proved to be very close to the predicted value of 13.70 mg/g from the quadratic model, with a regression coefficient of 0.969. This model also showed highly significant effects from changing frequency and time, and less significant effects from changing temperature. The extract from the optimized process showed 89.5% of higher DPPH radical scavenging activity than 71.3% from the conventional process. It was also found that the antioxidant activity of the extract was higher than that of using 13 µg/mL of C3G alone, possibly due to the synergistic effects of C3G with the other bioactive substances in the extract. Therefore, this optimized nonthermal process will be applied to obtain fairly high amounts of a thermally unstable and expensive C3G with fewer purification steps.