Recovering high value-added anthocyanins from blueberry pomace with ultrasound-assisted extraction

•Food waste blueberry pomace offers a high potential to recover anthocyanins.•Ultrasonic-assisted extraction of anthocyanins was optimized by Box-Behnken design.•The optimal parameters of ultrasonic treatment were 40 °C and 400 W for 40 min.•Highly purified blueberry anthocyanins were obtained after SCX cation exchange.•Malvidin was the main anthocyanins in the purified fractions from blueberry pomace.