Studies On Preparation And Application In Microcapsule Of Cross-linked OSA Heat Treatment Cassava Starch

This paper was mainly studied the preparation, properties and application of modified cassava starch. Firstly, the modified cassava starch was prepared by heat treatment, cross-linked with sodium trimetaphosphate(STMP), and esterified with octenyl succinic anhydride(OSA). The synthetic technological condition was researched and optimized. Also analyzed the structure and physicochemical properties of cross-linked OSA heat treatment cassava starch.As a new wall material used in oil microcapsule, researched the properties of microcapsule.Under acid condition, treated the native cassava starch with heat at140℃.To obtain appropriate heating time of cassava starch, with polarizing microscope and X-ray diffraction, studied on the granule morphology, crystal structure of thermal processing cassava starch, combined with the apparent viscosity. The results showed that the heating6h of cassava starch was suitable requirements.Heat treatment cassava starch as raw material, STMP as cross-linking agent, the cross-linked heat treatment cassava starch was prepared by wet method. As measured by the phosphorus content, determined the optimal process conditions were system pH11, the amount of STMP2%, reaction time2hours, reaction temperature40℃. Under this condition, the phosphorus content was0.03674%.On the base of cross-linked heat treatment cassava starch(P%was0.03674%), degree of substitution (DS) as evaluation index, esterified with OSA was investigated. On the base of single factor experiment, the process conditions for esterified starch were optimized by response surface methodology. The results showed that the optimal conditions as follows:starch slurry concentration40.04%, pH8.55, reaction temperature31.87℃, reaction time3.14hours. The DS of OSA starch under this condition was0.01998.The structure of esterified and cross-linked heat treatment starch were studied by fourier infrared spectrometer, X-ray diffractometer and environment scanning electron microscope. The results showed that no characteristic absorption peak of the phosphorus carbonyl owing to low content of phosphorus. But characteristic absorption peak of ester carbonyl groups at1724cm-1. X-ray diffraction and SEM graph showed that cross-linking reaction and esterification reaction only occurs in the amorphous region of the surface of the starch granules, and crystalline structure which did not damage after cross-linking and esterification.The physicochemical properties of cross-linked OSA heat treatment cassava starch were explored, the results showed that compared with native starch, the cross-linked OSA heat treatment cassava starch have lower viscosity, better transparency, anti-coagulant, and insoluble in cold water. After modification, solubility was increased at higher temperatures; what’s more, the emulsifiability and emulsion stability was greatly improved.Preparing microcapsule with cross-linked OSA heat treatment cassava starch as emulsifying wall materials by spray-drying method, determined the amount of modified cassava starch was8%. Studied the effect of homogenization pressure on microcapsule, combined with the actual, determined the homogenization pressure of the emulsion of the microcapsule was40MPa. Then embedding ratio of94.59%, which the content of surface oil was low. The reconstituted emulsion of microcapsule displayed a narrow particle size distribution spectrum. Microcapsule particles were spherical, smooth, morphological uniformity.