Response surface optimization of ultrasonic-assisted pigment extraction from Coreopsis tinctoria

Response surface methodology (RSM) was used to optimizing the ultrasonic-assisted extraction technology of pigment from Coreopsis tinctoria. The results showed that the flavonoids were the main constituents of the pigment Based on single factor experiments, a four-factor-level experiment design were developed by box-benhnhen central composite design method with causal factors of ultrasonic temperature, ultrasonic time, ratio of liquid to raw material, the concentrations of ethanol in solvent and the extract absorbance value for the response. The interactive effects of four crucial technological parameters were assessed by response surface methodology (RSM). The optimum ultrasonic-assisted extraction conditions were as follow: ultrasonic temperature was 70 °C, ultrasonic time was 60 min, the concentrations of ethanol in solvent was 72.25% and the ratio of liquid to raw material was 32.05:1 mL . g-1. Under the optimum extraction technology conditions, the absorbance value was 0. 936. The conditidns are suitable for the extraction process regression analysis and parameter optimization.