Relationship Between Preparation Conditions And Physicochemical Properties And Substituent Distribution Of Cationic Starch

Reaction conditions and preparation process are factors that influence the substituent distribution in starch molecular and starch physicochemical properties and application.Based on the previous research,cationic starches were modified in wet,ultrasonic pretreatment wet,dry,and microwave dry processes.Electron microscopy,X-ray diffraction,Differential scanning calorimetric and Rapid viscosity analyzer were used to study the influence of the reaction conditions and process on the physical and chemical properties of cationic starches.The starch derivatives were hydrolyzed by a-amylase,?-amylase,pullulanase,and amyloglucosidase.The distribution of substituent along the polymer chain was investigated by characterizing the hydrolysis products obtained by means of Electro Spray Ionization Quadruple-Time of Flight Mass Spectrometry(ESI/Q-TO-FMS/MS)and High-Performance Size-Exclusion Chromatography(HPSEC).Cationic groups distribution over the crystallization region and amorphous region were investigated by acidolysis at low temperature.The results showed as follows:1.The relationship between the reaction conditions and the physicochemical properties of cationic starch prepared by dry process.Molecular weight of dry cationic starch amylopectin were significantly negatively correlated to the dosage of cationic reagent,degree of substitution and reaction efficiency,the amylopectin content of dry cationic starch also with them into a very significant negative correlation.The content of amylose and low molecular weight fraction of caionic starch were significantly positively correlated to them.With the increasing dosage of cationic reagent,amylopectin of cationic starch were degraded into low molecular weight components.This increased the starch reaction activity increased,the reaction efficiency and the degree of substitution.Gelatinization temperatures and gelatinization enthalpy of dry cationic starch were negativel y correlated with reaction temperature and alkali dosage significantly,and negatively significantly correlated with the dosage of cationic reagent,and positively significantly correlated with the a mylopectin content,and negatively correlated with the molecular weight and the content of low molecular weight fraction.The crystallinity was positively correlated with the ?H.The increase of the reaction temperature and cationic reagent dosage and alkali dosage destroied the hydrogen bonds in the starch molecules,so as to reduced the length of the double helix structure of amylase and the molecular ordering degree,and the amylopectin of cationic starch were degraded.A largeamount of alkali catalyst can damage the structure of the crystalline structure of the starch crysta l.These changes were accompanied by a increase in the degree of substitution and reaction efficiency.Peak viscosity of dry cationic starch were positively correlated with degree of substitution a nd reaction efficiency,and negatively significantly correlated with the molecular weight and the content of low molecular weight fraction,and highly positively significantly correlated with the amylopectin content.Final viscosity(FV)and the water content into a highly significant negative correlation.With the increase of the reaction activity,the amylopectin of cationic starch were degraded into the lower molecular weight chain segment,and the peak viscosity of the paste was signif icantly increased.The cationic starch pastes with higher final viscosity can be obtained by reducing the water content of the dry process system.2.The relationship between the reaction conditions and the physicochemical properties of the wet cationic starch.The molecular weight of low molecular weight fraction was significantly positively correlated with reaction time,and it was positively correlated with the degree of substitution and reaction efficiency.As the reaction time increased,the amylopectin was gradually degraded into low molecular weight chain segments,and accompanied with the improvement of the degree of substitution and reaction efficiency.Gelatinization temperatures of wet cationic starch were negatively correlated with reaction ti me and cationic reagent dosage significantly,and negatively significantly correlated with the degree of substitution and reaction efficiency,and highly positively significantly correlated with the a mylopectin content,and highly negatively correlated with the molecular weight and the content o f low molecular weight fraction.Gelatinization enthalpy was negatively correlated with cationic reagent dosage significantly,and negatively significantly correlated with the degree of substitution and reaction efficiency,and highly positively significantly correlated with the amylopectin content,and highly negatively correlated with the molecular weight and the content of low molecular weight fraction.The crystallinity was positively correlated with the ?H.Peak viscosity of dry cationic starch was positively significantly correlated with pH value of reaction system.Trough viscosity was negatively significantly correlated with the molecular weight of amylopectin.3.The relationship between the preparation technology and the physicochemical properties o f cationic starch.The substitution was mainly occurred in the non crystalline region of dry and wet cationic starch under substitution degree 0.05.With the increase of the degree of substitution,there was a trend of the erosion of the crystalline region.Compared with the wet process,the destruction of dry process to the double helix structure of the starch crystalline region is larger,and the damage of the starch granule morphology is greater.The degradation of amylopectin was more greatly by wet process.The peak viscosity of dry cationic starch was higher than that of wet sample,and the difference between final viscosity and wet method was not significant.The pasting temperature of dry cationic starch was significantly lower than that of wet sample.4.The relationship between the reaction conditions and process and the distribution of cation ic starch substituted groupsCationic groups were more located in the amylopectin than amylose.Substituents were unevenly distributed over the amylose and amylopectin.Cationic starch with high substitution degree was found to have more homogeneous distribution.Reaction conditions and processing steps affect the substituent distribution in starch molecule and super-molecular structures.Cationic groups of high temperature dry cationic starch were found to be located near the branching point,and in the external chain of amylopectin.Low temperature dry cationic starch was found to have more homogeneous distribution of substituents than high temperature.The substitution groups in the wet sample were more likely to attack the branching region of the branched chain starch than the dry method.The position of the substituted group of ISO alcohol sample is more dispersed and tends to distribute at the end of the side chain of the branched chain starch.The MS\MS results showed that the concentration degree of substitution groups of cationic starch in different processes was: Ultrasonic wet process >microwave dry process > dry process.The results of low temperature acid hydrolysis of cationic starch showed that the substitution of the microwave dry process was more close to the non reducing end of the particle outer layer,followed by the wet and dry method.5.Relationship between Preparation Conditions and distribution of substituent groups and physical and chemical properties of cationic starchThe substitution groups of wet cationic starch in the amorphous region were more than that distributed in the amorphous region.The distribution pattern of the substituted group at the amylopectin leads to a large amount of degradation of the amylopectin.Eventually,the peak viscosity and final viscosity of cationic starch paste decreased,and the pasting temperature decreased.The substitution groups of cationic starch in dry process are more likely to enter the crystalline region.The distribution of amylose and amylopectin is more uniform.This distribution model makes the starch degradation less,the viscosity of the paste and the paste temperature is relatively high.