Study On The Optimum Conditions For The Preparation Of Hydroxypropylated-Phosphate Corn Starch

In this thesis, different factors to DS'effects,establishing mathematical model and optimuning for the preparation that was with hydroxypropylate corn starch were systematically studied during the preparation process. Get the optimum conditions for the preparation of hydroxypropylated-phosphate corn starch. Then targets and properties of different corn modified starch compared to its.Hydroxypropylated-phosphate corn starch was produced with hydroxypropylate corn starch by the semidry process, which was prepared by composite phosphate. We studied the different factors in the preparation process influencing degree of substitution (DS) of hydroxypropylated-phosphate corn starch, which include the rate of esterification, Ph ,the reaction temperature,the reaction time and the dosage of catalyst. By one-factor experiments, we can certain factors and range of level. Then we selected DS as the experiment index, using the five-factors quadratic regression orthogonal rotary method, and the optimum preparation conditions were obtained as follows: the rate of esterification 3.2:1, pH6.2~6.5, the reaction temperature 140~146℃, the reaction time 3~3.2h and the dosage of catalyst carbamide 3.6~4% of dry starch weight. The DS of final products were about 0.016.Hydroxypropylated-phosphate corn starch was prepared. Its targets and properties accord with standard of modified starch targets and properties, and its the temperature of Paste melting is lowest in corn starch,phosphate corn starch and hydroxypropylate corn starch. Congeal-the sinking of hydroxypropylated-phosphate corn starch is the worst. Its freeze-thaw stability is better than before. It is between phosphate corn starch and hydroxypropylate corn starch. Both phosphate corn starch and hydroxypropylate corn starch have better properties of freeze-thaw stability, so it has.