Optimization of the microwave-assisted extraction and antioxidant activities of anthocyanins from blackberry using a response surface methodology

Blackberry contains high amounts of anthocyanins, whose extraction method is closely related with anthocyanin content and antioxidant activity. The extraction yield and antioxidant capacity acted as the comprehensive evaluation indexes, and a Box–Behnken design (BBD) of response surface methodology (RSM) was employed to further optimize the microwave-assisted extraction (MAE) conditions for blackberry anthocyanins (BBAC). A significant correlation was found between the double indexes extraction yield and the antioxidant capacity (P < 0.01). The results showed that the optimized extraction conditions included a microwave power of 469 W, a solvent concentration of 52%, a liquid–solid ratio of 25 g mL−1, and a microwave time of 4 min. Under these conditions, the mean experimental value of the extraction yield (2.18 ± 0.06 mg g−1), ABTS assay (32.18 ± 1.54 μM TEAC per g) and DPPH assay (27.18 ± 1.33 μM TEAC per g) corresponded well with the predicted values. Moreover, these mean experimental values were 120% higher than those obtained during ethanol leaching extraction.