Preparation And Characterization Of Dual-modified Starches With Hydroxypropyl And Octenyl Succinate Anhydride

The preparation of dual-modified waxy corn starch was studied by two kinds ofreaction sequences respectively, esterification with octenyl succinate andetherification with hydroxypropyl. The physical–chemical characters of thedual-modified starches and the application of low viscosity dual-modified starches asmicrocapsule wall materials were researched systematically. In the following, detailedprocesses and results of the study were presented.The effect of the sequences of these two kinds of modification methods on thedegree of substitution were studied. The results were showd that, the preparation ofdual-modified starches, esterified with octenyl succinate anhydride firstly andetherified with hydroxypropyl later, made negative effect on the degree of functionalgroups; the preparation of dual-modified starches, etherified with hydroxypropylfirstly and esterified with octenyl succinate anhydride later, made positive effect onthe degree of functional groups. So that the method of etherification firstly followedby esterification reaction was considered as the optimal selection. The resultsindicated the suitable parameters for the preparation of esterification reaction were asfollows: concentration of starch slurry,35%(in proportion to water, w/w), reactionperiod,3h, pH of reactionsystem,8.5, reaction temperature,35℃.Compared with native starch and single modified starch, the physical–chemicalcharacters of the dual-modified starches, etherification firstly followed byesterification reaction, were investigated. The results were showed that, surfacemorphology and shape of the dual-modified starches were changed drastically, andmore suffered along with the higher levels of etherification, but The crystalline typewas not changed. The successful introduction of octenyl succinate (OS) groups wasproved by the appearance of some characteristic absorption peaks in FT-IR. Theemulsifying,and emulsion stability were improved after compound modification, andwere increased when the levels of esterification were higher.The transparency,freeze-thaw stability and apparent viscosity were improved after compoundmodification, and were increased when the levels of etherification were higher. The gelatinization temperature was dropped, and the peak viscosity was increased.The low viscosity dual-modified starches, preparation with high temperaturepyrolysis, as microcapsule wall materials were researched. The results were showedthat, the characteristic absorption peak in FT-IR, indicated no damage on the OSgroups of SSOS and compound modified starch after high temperature pyrolysis. Theapparent viscosity of composite modified starch was iproved, compared with the lowviscosity SSOS, and with the higher levels of etherification viscosity was increased.The surface oil and emabedding rate of powder oils had obviously improved,compared with low SSOS. When the corn wall ratio was1:6, powdered oils that itssurface oil was1.14%and embedding ratio was94.38%was successfully obtained.The low viscosity dual-modified starches, preparation with α amylase enzyme orβ amylase enzyme hydrolysis, as microcapsule wall materials were researched. Theresults were showed that, the surface oil and emabedding rate of powder oils hadobviously improved, compared with low SSOS.