Comparing of hot water and acid extraction of polysaccharides from proso millet

The extraction of polysaccharides from proso millet was investigated experimentally using hot water and acid aqueous solution. Response surface methodology, based on a three-level, three- or four-variable Box-Behnken design for hot water extraction or acid extraction, respectively, was employed to obtain the best possible combination of acid concentration, liquid-solid ratio, extraction time, and extraction temperature for maximum polysaccharides yield. The obtained experimental data were fitted to a second-order polynomial equation and analyzed by appropriate statistical methods. The corresponding optimum extraction conditions of each method were obtained. Under the optimum conditions, the experimental yield was well in close agreement with the predicted value by the model. The results showed that the polysaccharides yield of acid extraction was 42.13 mg g-1, significantly higher than 20.07 mg g-1 of the yield of hot water extraction, the obtained equation could be used to predict the extraction experimental results.