Studies On The Extraction Technology Of Taro Starch By Enzyme And The Properties Modified By Ultrasound Combined Malic Acid

Because of its excellent performance, composite modified starch has been widely applied gradually in various fields, and as a new physical modification of starch ultrasonic technique is also received extensive attention. In this study, taro starch was prepared by neutral cellulase hydrolysis from taro, modified starch was prepared by hydrolysis under combination of ultrasound and malic acid with taro starch as raw material. Study of its extraction technology, synthetic route, respectively, the optimum synthesis process parameters of the extraction technology of taro starch by enzyme and the compound modification on properties of ultrasound was optimized in preparation of composite modified starch process. To its structure, properties, at the same time made a detailed comparison research, provided a reference for the further development of compound modified taro starch, data for the application of ultrasonic technology in the modified starch production provide a certain basis and reference, to better use of ultrasound technology.At first, taro starch was prepared by the hydrolysis of neutral cellulase with taro as raw material. The effects of hydrolysis temperature, hydrolysis time, cellulase dosage and solid-liquid ratio were investigated, by an orthogonal experiment the optimal conditions for taro starch preparation were gotten as follows:enzymolysis temperature at 35℃, enzymolysis time at 4 h, cellulase dosage at 0.60% and solid-liquid ratio at 1:4.Modified starch was prepared by hydrolysis under combination of ultrasound and malic acid with taro starch as raw material. The effects of hydrochloric acid dosage, temperature, time, and ultrasound power were investigated. The optimal conditions were gotten by an orthogonal experiment. The result showed that, optimum process conditions of preparation of taro starch acid solution were as follows:the concentrated malic acid percent:40%, ultrasonic temperature:55℃, ultrasonic time:150 min, ultrasonic power:700 W.The surface morphology of synthetic product was analyzed by scanning electron microscopy (SEM); Using X-ray diffraction and infrared spectrometer indentified the crystal structure of synthetic product; The characteristics of the paste liquid was studied by Brabender pasting machine; and the physical and chemical properties,such as the thermal properties, particle size and transparency, solubility, freeze-thaw stability and retrogradation and so on, were researched in detail. The results were as follows:The starch granule surface was smooth, no holes, but when the starch was under acidolysis esterification compound modified, modified starch granule surface was rough, holes, grain was relatively concentrated, each other together; Compound modification without damage the original structure of starch molecules, but its infrared crystallization index than the original starch was reduced by 11.25%; The crystal structure of original starch was not destroyed, but the peak intensity of the diffraction characteristics of weakening. Various physical and chemical indexes had increased significantly, the transparency of the starch increased from 16.8% to 44.7%, solubility increased from 5.17% to 23.67%, bibulous rate was increased to 75.77 from 60.58% of the original starch, the starch of enthalpy value and retrogradation were lower than the original starch.