Study On Synthesis Of Carboxymethyl Rice Starch By Different Preparation Methods

A large number of overdue unhusked rice and broken rice produced due to mechanical injury and other reasons in rice processing,have a low application in the real life because of the taste,appearance,nutrition and other factors.In order to making the broken rice and overdue unhusked rice to play a greater role,it is particularly important to carry out the further processing.The content of starch and protein were abundant in rice,modern separation technology have been able to separate rice starch from rice protein,the further processing of rice starch into modified starch will broaden its application range.This thesis preparation of carboxymenthyl rich starch by solvent method and semi-dry method,the best process conditions obtained by single factor analysis,carboxymenthyl starch were analyzed by infrared spectrum and crystal structure,the physicochemical properties of carboxymenthyl rich starch compared with the rich starch.This study provides a theoretical basis and specific methods for the exploitation and utilization of brokrn rice.Carboxymenthyl rich starch was prepared by semi-dry method,used rich starch as raw material,and sodium chloroacetate was used as the etherification agent,and alkali was added step by step.The dosage of sodium chloroacetate,the dosage of Na OH,reaction temperature and time of etherification,reaction temperature and time of alkalinization conditions on the influence of the substitution degree of product were investigated.The results show that optimizing conditions of CMS by single factor experiment were starch and sodium chloroacetate of 1:1 in molar ratio,starch and sodium hydroxide of 1:1.25 in molar ratio,alkalinization temperature of 35 ?,alkalinization time of 1h and etherification temperature of 70 ?,etherification time of 2.5 h.The substitution degree of obtained CMS was 0.45 on above conditions.The infrared spectrum and crystal structure of carboxymethyl rice starch was characterized and analyzed by some methods such as FITR,SEM and XRD.Carboxymenthyl rich starch was prepared by solvent method,used rich starch as raw material,and chloroacetic acid was used as the etherification agent,and alkali was added step by step.The dosage of sodium chloroacetate,the dosage of Na OH,reaction temperature and time of etherification,reaction temperature and time of alkalinization conditions on the influence of the substitution degree of product were investigated.The results show that optimizing conditions of CMS by single factor experiment were starch and chloroacetic acid of 1:1.27 in molar ratio,starch and sodium hydroxide of 1:1.646 in molar ratio,alkalinization temperature of 50 ?,alkalinization time of 30 min and etherification temperature of 60 ?,etherification time of 4 h,the dosage of ethanol 90 ml.The substitution degree of obtained CMS was 0.68 on above conditions.The infrared spectrum and crystal structure of carboxymethyl rice starch was characterized and analyzed by some methods such as FITR,SEM and XRD.The physicochemical properties of carboxymethyl rice starch compared with rice starch.The experimental results showed that the physical and chemical properties ofrice starch were obvious changed after carboxyl methylation.The transparency of carboxymethyl starch increased,the solubility and swelling degree was significantly increased,the freeze-thaw stability was stronger,the anticoagulation sank ability was significantly improved,the greater the degree of substitution,the more obvious of these changes.The substitution degree of carboxymethyl rice starch was 0.68,the water separating proportion was up to 35.97%,the transmittance can reach 78.9%,the supernatant volume fraction was low to 20.1% after the starch paste was stewing,the solubility was 25.3% and the swelling degree was 42.7% at 100 ?.The physical and chemical properties of carboxymethyl rice starch were compared between solvent method and semi-dry method,the results indicated that the products prepared by the solvent method were better than the products prepared by the semi-dry method in the transmittance,freeze-thaw stability,anticoagulation sinking,solubility and swelling degree.For example,the substitution degree of carboxymethyl rice starch was 0.35,freeze-thaw cycles were 3 times,but the solvent method was lower than semi-dry method 3% in water separating proportion,it shows that the solvent method was better than the semi-dry method in freeze-thaw stability.Moreover,the transmittance of solvent method was 75.8% greater than the semi-dry method 74.4%,the supernatant volume fraction of solvent method was 34% less than the semi-dry method 46% after the starch paste was stewing.