Add a certain amount of sodium sulfate (as a swelling inhibitor) to a certain amount of water, stir and dissolve at 40°C, add a certain amount of wheat starch to make starch milk, then add a certain volume of sodium hydroxide solution, and seal , Add a certain amount of propylene oxide to an environment filled with nitrogen. After reacting for a period of time, adjust the pH value to 5.5 with 3% hydrochloric acid, centrifuge, wash with water, dry at 50°C, crush and sieving to obtain hydroxypropyl starch.
Optimization of the preparation process of hydroxypropyl starch
Hydroxypropyl starch is prepared by the aqueous medium method, with mild reaction conditions and low equipment requirements. It is the most commonly used and simplest method for preparing hydroxypropyl starch. Firstly, the single factor experiment was carried out with the degree of substitution as the inspection index. It was found that the main factors affecting the degree of substitution of hydroxypropyl starch were: the amount and ratio of anhydrous sodium sulfate and sodium hydroxide, the amount of propylene oxide and the reaction time. If the dosage of anhydrous sodium sulfate is too low, the starch will over-swell and gelatinize, which will cause difficulty in stirring and subsequent dehydration. If the dosage of anhydrous sodium sulfate is too much, the starch will not be fully activated, the reaction activity will decrease and the degree of substitution will decrease. It is advisable to control it at 15%~30%; if the amount of sodium hydroxide is too much, the starch is easy to gelatinize. If the amount is too low, the active groups formed by the starch in the alkalization process will be reduced, the reaction efficiency is low, and the degree of substitution is not high. It shows that it is appropriate to control the dosage range of 0.5%~2%; the increase in the amount of propylene oxide will increase the degree of product substitution, but the corresponding cost will increase, and the reaction efficiency will not rise but drop. The experiment shows that the dosage range is controlled within 20%~ 30% is appropriate; increasing the reaction time will increase the degree of product substitution, but the energy consumption will increase, and with the prolongation of the reaction time, the degree of substitution will decrease. Experiments show that it is appropriate to control the range at about 12h.
After being hydroxypropylated, wheat starch has higher light transmittance, anti-condensation, anti-aging, acid resistance, and salt resistance than native starch. It can be used as an ideal food additive in food production.
Post time: Dec-19-2020