Preparation And Properties Of Hydroxyethyl Rice Starch

China is the largest producer and consumer of rice in the world. During the processing, a large amount of broken rice was produced. With the development of science and technology, using broken rice as raw materials for preparing rice starch and rice protein hydrolysate have been industrialized, which improved the utilization rate of broken rice resources and promoted the application of rice starch. Defects in structure and physicochemical property of natural rice starch reduce its utilizability.Through modified starch, specific functions and characteristics were obtained, which expanded the scope of the application of starch. This paper studied the optimum conditions for preparation of hydroxyethyl rice starch, and its structural characteristics and physicochemical properties were analyzed.Hydrochloric acid hydrolysis rice starch to a certain molecular weight before hydroxyethylation, under the basic conditions of rice starch 10.0 g, water 30 ml,ultrasonic treatment 15 min, hydrochloric acid 2 mL(0.25 mol/L).The temperature is65 ℃, the stirring speed is 300 r/min, the reaction time is 1.5 h reached ideal range of kinematic viscosity(18.3 ~ 20.0 mm2/s). From the FTIR spectra, rice starch did happened acidification;From the XRD spectra, acidification mainly occurred in the amorphous region, the double effect of ultrasonic treatment and acidification are not enough to damage the crystalline areas; through the absorption spectra of starch iodine complex showed that with DE value of acid starch increased, the degree of hydrolysis increased, and the maximum absorbance gradually blue shifted slightly.Hydroxyethyl rice starch was prepared through solvent method combined with ultrasonic treatment. Through experiments reaction temperature, anhydrous ethanol,ethanol chloride, sodium hydroxide, reaction time of five single factors to hydroxyethyl molar substitution degree of influence has been studied. The results showed that under the basic conditions of the milled starch 10.0 g and distilled water30 mL, the optimun conditions were temperature of 50℃,sodium hydroxide of 2.4 g,chloride anhydrous ethanol of 50 mL, ethanol of 4 g and reaction time of 8 h.The structure characteristics of rice starch and hydroxyethyl starch were studied.From the FTIR spectra, rice starch did happened hydroxyethylation. The XRD and SEM results indicated that the etherification reaction of rice starch mainly occurred in the amorphous region did not change the crystal shape. After ultrasonic treatment andetherification, the crystal structure and particle morphology of indica rice starch were destroyed. The crystal structure of hydroxyethyl rice starch changed from A to V. By the TG-DSC diagram indicated that thermal stability of hydroxyethyl rice starch lower compared with the raw starch.The physicochemical properties of hydroxyethyl starch and rice starch were studied. The results show that with hydroxyethyl starch degree of substitution increased,anti-precipitability better, solubility increased, and starch paste transparency increased significantly. The absorbance of starch iodine complex decreased gradually,and the maximum absorption value blue shifted. UV-Vis absorbance decreased, and absorption bands were blue shifted relatively.