The invention relates to a method for preparing hydroxypropul
starch under
ultrasound and
microwave synergistic effect, belonging to the grain
processing field; cereal grains or yam
starch are used as
raw material, epoxypropane is taken as etherifying agent,
sodium hydroxide is taken as catalyst, and
anhydrous sodium sulfate is used as swelling restraining agent, and the hydroxypropul
starch is prepared under the
ultrasound and
microwave synergistic effect; the starch
raw material is prepared into starch milk with 10-50 percent of concentration by
mass ratio, and then the starch milk is placed in an ultrasonic wave reactor with 200W-800W of supersonic wave
electric power and 20kHz-500kHz of frequency,
ultrasound action is carried out for 10-60min, and then the starch milk is taken out, filtered and dried, and then the starch milk is mixed with 0.2-0.4 percent of
sodium hydroxide, 1.0-3.0 percent of the
anhydrous sodium sulfate and 2.0-7.2 percent of epoxypropane, the mixture is fully stirred and mixed uniformly, and then the mixture is placed in a
microwave reactor for reaction, the
microwave power is 60-300W, and the
microwave action time is 2-20min; after the reaction is carriedout, the
reaction product is taken out and is neutralized by HCL with 1mol / L until the pH value is 5.5-6.0, and then the
drying is carried out, so as to obtain the hydroxypropul starch with 0.01-2.00of molecule substitution degree; in the method, the reaction time is short, the efficiency is high, the product quality is good, the molecule substitution degree can be adjusted in a
large range, andthe application range is wide.