Optimization of microwave-assisted extraction conditions of DPPH radical scavenging components from Porphyra yezoensis by response surface methodology

Response surface methodology (RSM) was applied to predict optimum conditions for microwave-assisted extraction (MAE) of antioxidantive components from P. yezoensis. 1,1´-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay was used to evaluate the activity of antioxidantive components. Keep the ratio of water to material (mL/g) 50:1, a Box-Behnken design was used to monitor the effect of microwave power (300-700 W, X₁), extraction temperature (50-70 °C, X₂) and extraction time (4-8 min, X₃) on the dependent variable, DPPH free radical scavenging activity of P. yezoensis extract. The optimal conditions to achieve the maximum activity of antioxidantive components were determined as follows: microwave power 500 W, extraction temperature 62 °C, extraction time 6.3 min. Under these optimal conditions, the DPPH free radical scavenging activity of antioxidantive components was 68.3%. Estimated maximum value at predicted optimum conditions were in good agreement with experimental value.