Research On Preparation And Functional Properties Of Corn Starch Sulfate By Ultrasonic Method

In this paper, the corn starch was used as raw material and trisulfonated sodium amine （N（SO₃Na）3） synthetized by NaHSO₃and NaNO₂as esterification agent, the corn starch sulfate wasprepared by the ultrasonic method. The physicochemical properties and bioactivities of corn starchsulfates were determined in order to provide the theoretical basis for industrial production anddiverse application expecially in the medical field.Firstly, the process conditions of esterification agent and synthesis of corn starch sulfates wereresearched. By single factor experiment, we studied the effects of the molar ratio （nNaHSO₃/nNaNO₂）,synthesis temperature and time on esterification agent. The results showed that the syntheticconditions of esterification agent were summarized as follows: nNaHSO₃/nNaNO₂was4.25, thepreparation temperature was90℃and the preparation time was90min. Then we studied theeffects of addition of water, pH value, addition of starch, the temperature, time and power ofultrasound on the degree of substitution （DS） and synthetic efficiency of corn starch sulfates. Byorthogonal test, the optimal synthetic conditions of corn starch sulfates by ultrasonic method wereobtained: addition of esterification agent was52.5mL, addition of water was17.5mL, pH was9,addition of starch was69%, ultrasound temperature was45℃,ultrasound time was40min andultrasound power was120W.Secondly, the physicochemical properties and structures of corn starch sulfates were studied.The results showed that the solubility and transparency of corn starch sulfates were elevated withthe rise of DS, and the freeze-thaw stability was enhanced with the rise of DS. The analysis of RVAindicated that the peak viscosity, minimum viscosity, final viscosity, crumbling value and backvalue were all decreased with the rise of DS; the peak time and pasting temperature were increasedwith the rise of DS under the lower DS and changed into disorder under certain DS. FTIR spectrumshowed-OH of corn starch was linked up with–SO₃H of trisulfonated sodium amine （N（SO₃Na）₃）by the characteristic absorption peak of1241cm^-1and807cm^-1; X-ray diffraction patterns showedthat the crystal structure of corn starch sulfates was destroyed and degree of crystallization reduced,but the crystallization type of corn starch sulfates still remained unchanged; optical microscopyimages showed that corn starch sulfates still had polarization cross, the surface of particles wereadhered by a lot of pieces, and some carbon chains of starch were ruptured; measurement ofmolecular weight showed that molecular weight was reduced with the rise of DS.Thirdly, bioactivities of corn starch sulfates were studied. The corn starch sulfates showedgood anticoagulant effect in anticoagulation tests in vitro, anticoagulation time was obviouslylengthened when the DS reached and exceeded0.446. The corn starch sulfates showed goodoxidation resistance in antioxidative model in vitro, and presented stronger reducing power,chelating ability of ferrous ion, scavenging activities of hydroxyl and superoxide radicals. Thereduction of molecular weight enhanced antioxidative abilities under certain DS. Inhibitory abilities and inhibitory type of corn starch sulfates on α-glucosidase （AGC） in vitro were also investigated.Results suggested that corn starch sulfates showed good inhibitory abilities for α-glucosidase, andwas a competitive inhibitor. Inhibitory effect of corn starch sulfates on angiotensin convertingenzyme （ACE） were carried out and corn starch sulfates had been proven a good inhibitor for ACE.Besides, the inhibitory effect was greatly enhanced with the reduction of molecular weight. Allthese results could evidence that corn starch sulfates performed hpyerglycemic effect and couldprevent or relieve hypertension of diabetics.Corn starch sulfates were chemically modified by corn starch with trisulfonated sodium amine（N（SO₃Na）₃）.This synthese was completed by ultrasonic method.At first,physicochemical propertyof corn starch sulfates were researched and which bioactivity were preliminary inquiried.Expectations were that this studied could provide the theory basis for industrial production and useof diversification,expecially for application in medicine.