Comparison Three Auxiliary Methods For The Preparation And Properties Of Hydroxypropyl Corn Starch

The preparation of three different methods for preparation of hydroxypropyl corn starch synthesis process was studied by using corn starch as raw material, epoxy propane as etherifying agent, sodium hydroxide as catalyst and anhydrous sodium sulfate as the inhibition of expansive agent, and the compared the physical and chemical properties of the product, in order get higher degree of substitution and better performance of hydroxypropyl corn starch, as to provide theoretical basis for practical application.In traditional method, through the single factor experiment, the preparation of hydroxypropyl corn starch to get optimal process condition is:amount of propylene oxide was 10%, amount of sodium hydroxide was 1%, sodium consumption is 12%, the optimum reaction temperature 45℃, reaction time is 16 h, under the condition of the preparation of hydroxypropyl corn starch substitution degree of 0.091.In the ultrasonic method, optimized by single factor experiment and orthogonal analysis, get the optimal technology conditions for preparation:ultrasonic power is 500 W, ultrasonic time is 25 min, starch milk concentration is 40%, the amount of 12% propylene oxide, reaction temperature was 40℃, the reaction time is 6 h, under the condition of the preparation of hydroxypropyl corn starch substitution degree of 0.182.In the irradiation method, influences of some factors on hydroxypropyl corn starch were investigated, including radiation dosage, starch concentration, epoxy propane dosage, sodium hydroxide dosage, sodium sulfate dosage, reactive temperature and reactive time. Then through the orthogonal experiment, the reaction conditions were optimized as follows: radiation dosage 7 KGy, starch concentration 45%,epoxy propane 12%, sodium hydroxide 1.0%, temperature 45℃ and reaction time 8 h. Under the above conditions, the molar substitution degree of hydroxypropyl com starch was 0.27.Compare three methods, the ultrasonic method takes the shortest, product substitution degree is higher and irradiation method is also time consuming short, substitute degree of the product.When physicochemical properties of the three methods for preparing hydroxypropyl corn starch found, three methods to preparation the same substitution degree of hydroxypropyl starch gelatinization temperature, ultrasonic method and irradiation of of hydroxypropyl starch solubility and light transmittance, and were higher than the traditional method, irradiation of the preparation of hydroxypropyl corn starch drainage rate is the lowest, best explain the freeze-thaw stability, and high viscosity.