Optimization of microwave-assisted extraction (MAP) for ginseng components by response surface methodology

Response surface methodology (RSM) was applied to predict optimum conditions for microwave-assisted extraction-a MAP technology-of saponin components from ginseng roots. A central composite design was used to monitor the effect of ethanol concentration (30-90%, X-1) and extraction time (30-270 s, X-2) on dependent variables, such as total extract yield (Y-1), crude saponin content (Y-2), and saponin ratio (Y-3), under atmospheric pressure conditions when focused microwaves were applied at an emission frequency of 2450 MHz. In MAP under pre-established conditions, correlation ;coefficients (R-2) of the models for total extract yield and crude saponin were 0.9841 (p < 0.001) and 0.9704 (p < 0.01). Optimum extraction conditions were predicted for each variable as 52.6% ethanol and 224.7 s in extract yield and as 77.3% ethanol and 295.1 s in crude saponins, respectively. Estimated maximum values at predicted optimum conditions were in good agreement with experimental values.