Preparation and characteristics of phosphate monoesters of sweet potato starch.

Starch phosphate monoesters were prepared with sweet potato starches by wet process,and its physical and chemical characteristics were researched.The regression equation describing the relation between degree of substitution(DS) and preparation conditions was obtained by using the five-factors quadratic regression orthogonal rotary combination method.The optimum parameters for the preparation of phosphate monoester of sweet potato starch was selected as follows: the molar ratio of Na2HPO4 and NaH2PO4 was 3∶1,the reaction temperature was 130-140 ℃,reaction time was 2-3 h,pH value was 5.5-6.0,and catalyzer dosage was 4%-5% of starch mass.The results of characteristics showed that the retrogradation of esterized starches weakened and their paste clarity and freeze-thaw stability improved as phosphate groups were linked with the anhydrous glucose units after esterization.