Synthesis Of Octenyl Succinic Acid Starch Ester And Octenylsuccinylation Kinetics Of Starch In Aqueous Slurry

In this paper, technical condition of the preparation of octenyl succinic acid starch easter (OSAS) in aqueous slurry system was discussed, structure and characteristics of OSAS were studied, and octenylsuccinylation kinetics of starch in aqueous slurry was investigated.The influential factors of degree of substitution (DS) including concentration of octenyl succinate anhydride, water content, reaction time, pH and reaction temperature were studied by uniformity design method. With the destination of DS, polynomial regression equation was established and analysed. Physicochemical properties including whiteness, retrogradation, freeze-thaw stability, viscosity, clarity, emulsibility of OSAS and native starch were discussed. Structure of OSAS was characterized by FTIR, XRD, SEM and etc. The kinetics of esterification of starch in aqueous slurry system was investigated by model assumption, deriving and experimental verification. The results were as followed:The orders of influential factors on DS were as followed:reaction time>concentration of OSA>reaction temperature>pH>water content. With the method of Monte Carlo, the best conditions were as followed:pH value was 9.66, reaction time was6h, reaction temperature was50℃, concentration of OSA was17.84%. The degree of substitution of OSAS was0.04955under these conditions.The physicochemical properties including whiteness, retrogradation, freeze-thaw stability, viscosity, clarity, emulsibility of OSAS were much better than native starch. The results of FTIR, XRD, SEM and DSC showed that the esterification was occur between OSA and starch. The esterification was in the amorphous regions of starch. The heat stability of OSAS was worse than native starch.The models of octenylsuccinylation kinetics of starch in aqueous slurry were as followed:Esterification of starch:r1=k1CACAGu=4.522×105e-50310/RTCACAGUHydrolysis of OSA:r2=k2CACOH=9.102×106e-24380/RT CACOH-Deesterification of OSAS:r3=k3CBCON-=3.863×1011e-73063/RTCBCOH-The selectivity of esterification was related to temperature, pH valuable and concentration of starch. The elevated of temperature and concentration of starch were helpful for the selectivity of esterification, and the rose of pH valuable was unfavorable to the selectivity of esterification.The DS of OSAS was related to reaction temperature, time, concentration of alkali, initial concentration of OSA. The improvement of reaction temperature, time and initial concentration starch and OSA were helpful for the improvement of DS, and the concentration of alkali and initial concentration of starch were unfavorable to the improvement of DS. The analysis results of uniform design model were basically in an agreement with the kinetic model.