| The dry preparation technics of amphoteric starch with corn starch as raw material and the granules properties and paste properties of amphoteric starch was studied in this paper .The main results were as follows:1.The studies of dry preparation technics of amphoteric starch.The proper technology parameters were obtained through single factor test. Cation starch: NaOH/GTA = 2.35, reaction temperature = 75℃, reaction time = 3h, water content in system = 20%. Amphoteric starch : ClCH2COOH/cation starch=0.06,NaOH/ClCH2COOH=3, reaction temperature = 70℃, water content in system=24%, reaction time=3h.Water content ,reaction temperature, reaction time in system were selected in orthogonal test of cation starch. NaOH/ClCH2COOH, reaction temperature,reaction time,water content in system were selected in orthogonal test of amphoteric starch. The proper technology parameters for the process were obtained: for cation starch, water content in system=20%, reaction temperature=70℃, reaction time=3h; for amphoteric starch, water content in system = 24%, reaction temperature = 75℃, reaction time=2.5h, NaOH/ClCH2COOH=3.2.The properties of amphoteric starch.The granules properties and paste properties of amphoteric starch with different DS and cationic starch were compared,the conclusions were as follows:Amphoteric starch had better hot and cold stability compare with cationic starch. cation replace degree and A/C had singnificant influence to paste viscosity of amphoteric starch.Carboxylic amphoteric starch paste had better stability against acid and alkali,shearing and better freeze-thaw stability,higher clarity.Caboxymethylation and cationation took place not only in the amorphous regions but also in the crystalline regions .
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