Study On Preparation Technology Of Low Degrees Of Substition Of Purple Sweet Potato Starch Acetates By Ultrasound-enhanced Method

In this paper,taking purple sweet potato starch after extract the pigment as raw materials for the preparation of starch acetates with low degrees of substitut, respectively using the traditional method and the ultrasound-enhanced method to produce, then research the best process parameters of the two method. Compare the two kinds of production processes and the processing properties of the modified starch and the natural starch. Providing useful reference in purple sweet potato starch processing, and the application of ultrasound. Results are as follows.1.The low substitution degrees acetate starch was obtained from purple sweet potato starch by traditional method. The factors of reaction efficiency such as reaction temperature,reaction pH value, reaction time and the consumption of acetic anhydride were investigated, and processing properties of acetic starch was studied. Through a series of single factor experiments and the L9(34) orthogonal experiment, results showed the optimum preparation conditions were:reaction temperature 30℃, pH value 8.5, acetic anhydride 6%, reaction time 60min, the degree of substitution was 0.0806. Starch acetate transparency, film-forming, crosslinked starch were better than the original.2.The low substitution degrees acetate starch was obtained from purple sweet potato starch by ultrasound-enhanced method.This article adopted the L9(34) orthogonal experimental design based on the single-factor test to study the effects of ultrasound power, ultrasound time and ultrasound temperature on the substitution degrees of purple sweet potato acetate starch. Results showed the optimum technological conditions were confined as follows:ultrasonic power 75W, ultrasonic time 25min, ultrasonic temperature 40℃,which could prepare acetate starch of 0.1049 substitution degrees.3. With the best process parameters of the traditional method and the ultrasound-enhanced method to produce the similar substitution(DS=0.0806) of the purple sweet potato starch acetate. In the ultrasonic power 75W, ultrasonic time 25min, ultrasonic temperature 40℃,water bath time 18 min, the total reaction time was 43min. Compared traditional method which need lh,it increase 17min using the ultrasound-enhanced method.4.Compared to the non-ultrasonic acetate starch, the retrogradation of the ultrasonic acetate starch all declined, but viscosity of paste、transparency and freeze-thaw stability enhanced.