Quantitative Analysis Of The Crosslinking Reaction Between Starch, Gliadin With Citric Acid

Carboxylic acids such as citric acid are inexpensive and nontoxic chemicals preferred for crosslinking proteins and cellulose to improve the desired properties of the materials. In this study, citric acid was used to crosslink starch and gliadin.Starch was crosslinked with citric acid at different temperature, different time. Conductivity titration and HPLC were used to determine the amount of carboxyl groups on the starch. The influence of the amount of reacted carboxyl groups in each CA molecule on the tensile strength and thermal stability was studied with IR, TG The kinetic parameters, such as reaction order, the reaction rate constant and the activation energy Ea of the crosslinking reaction have been obtained at different temperatures.In this study, gliadin was chosen as a model of plant proteins because it contained relatively more amine side groups that can react with a carboxylic acid crosslinker than other plant proteins. A dry state crosslinking of gliadin films with citric acid was studied. A relationship between the mechanical properties and the crosslinking degree has been developed. The influence of the concentration of citric acid and pH on the tensile strength was studied. SDS Electrophoresis was used to analysis the molecular weight of the gliadin before and after crosslinking. Alkaline catalyzed crosslinking of gliadin powders in aqueous citric acid solutions at low temperatures was employed. Conductivity titration and Potentiometric titration method was used to investigate the influences of reaction temperature on both carboxyl and amine group changes during the reaction. The kinetic parameters of wet reaction states have been obtained at different temperatures.