A response surface method (RSM) was employed to optimize polysaccharide extraction from Panax japonicus (PJPS). Also, carboxymethyl substitution of PJPS (CM-PJPS) was studied using a response surface methodology. A three-variable Box– Behnken design (BBD) methodology was applied. RSM analyses revealed that conditions that maximized polysaccharide yield were as follows: a liquid-to-material ratio 22:1, an extraction temperature of 83.99 °C and an extraction duration of 2.32 h. Under optimum extraction conditions, the average absorbance value o...