Optimization for processing parameters of Coix starch extracted with ultrasound- microwave by response surface methodology

In this study,the effect of ratio of material to liquid,mass concentration of Na OH solution,extraction temperature,microwave power and extraction time on extraction rate of Coix starch was studied by ultrasound-microwave synergistic extraction.Based on single factor experiments,the Coix starch optimized by response surface methodology was obtain of various process parameters.The results revealed that the optimum extraction process parameters for ultrasound- microwave synergistic extraction of Coix starch included ratio of material to liquid of 1∶ 9( g / m L),the mass fraction of Na OH solution of 0.30%,extraction temperature of 34 ℃,microwave power of 134 W and extraction time of 150 min.In this optimal condition,the extraction rate of starch was up to93.15%,which was close to the theoretically predicted value by confirmative experiment,and the established model fitting degree was good.The method studied in this paper compared with traditional alkali extraction methods,microwave- assisted method and ultrasonic- assisted method,the extraction rate of Coix starch increased of18.97%,12.78%,10.35%,respectively.The ultrasound- microwave synergistic extraction is found to be timesaving and efficient which may be utilized for the extraction of Coix starch.