| Octenyl succinate starch, a new kind of modified starch, is an production ofesterified starch with octenyl succinic anhydride on alkaline conditions. Octenylsuccinate starch is a safe emulsion and thickener，can be used as emulsion stabilizer,microcapsule materials, components of the cosmetic etc. There are three kinds oftechnology of preparation of the octenyl succinate starch: water phase, dry technique,organic phase.Commonly people use the water phase to prepare this modified starch.The degree of substitution of the production will be low in this way. Many reportsshow the lipase can catalyze the esterification in organic solvent. This article focuseson the preparation of the octenyl succinate starch in organic phase with lipase.(1) Esterification of cassava starch and octenyl succinic anhydrideThis section studied the optimum technological conditions of the esterification.The raw materials are cassava starch and octenyl succinic anhydride, with thecatalyst-lipase. Choose mixed solution of water and hexane as the medium of thesynthesis. The impact of various process parameters on the degree of substitution wasdiscussed. The suitable parameters were as follows：reaction temperature40℃，reactionperiod20min, hexane:water is9:1, lipase0.5%(in proportion to dry starch), amount ofOSA3％(in proportion to dry starch)．The degree of substitution was0.2114.(2) Enzymolysis and ion-exchange column chromatography of octenyl succinatecassava starchThe starch molecules with octenyl succinic anhydride molecules were isolatedusing DEAE-cellulose column chromatography.Unreacted starch molecules wereeluted off the column first with buffer while those having anegative charge from OSAwere eluted afterwards with a0-2M NaCl gradient. DEAE cellulose chromatograms ofpullulanase digested OSA-starch are shown the same result. Unmodified starch isdigested by pullulanase into starch branches were eluted. For OSA-starch of D.S.0.02,elutes near the void volume and these starch molecules have a largehydrodynamic volume and hence high molecular weight.(3) The properties of octenyl succinate cassava starchStudied the transparency, solubility, freeze-thaw stability, emulsification of octen-yl succinate cassava starch. The results showed that the viscosity, emulsification and clarity of octenylsuccinate cassava starch slightly increased with DS, the freeze-thaw stability of octenylsuccinate cassava starch was weakned. Octenyl succinate anhydride starch gel isshear-thinning which should belong to pseudoplastic liquid.(4) Application of the octenylsuccinate cassava starch in the preparation of yoghurtUsed octenyl succinate cassava starch ester in the preparation of yoghurt.Compar-ed the difference in taste, viscosity and other properties of yoghurt between the onewhich added octenyl succinic cassava starch ester and which did not added. |
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