Studies On The Preparation Of Two Kinds Of Acetate Starches With Environment-friendly Technology And Their Properties

Processes of acetate starch are improved for environmental protection and energy saving. Microwave and Infrared heating technologies were adopted in the starch to maintain constant temperature, which is conductive to produce Stable-Quality acetate starch. Test results showed the approach provided in this thesis is a potential method for mass production. In this paper, Using the microwave far-infrared solid-phase continuous reactors, corn starch, potato starch, study of the preparation process of etstarch acetate, modified starch structure characterization, physical and chemical properties and application properties.The main conclusions was as follows:(1) Addition of acetic anhydride, reaction temperature, reaction time, volume and moisture content on starch acetate etherification were examined separately, while leaving other factors as they were during the experiment, process for the preparation of starch was optimized using quadratic general rotary. Test results showed: for corn starch, the optimum condition is acetic anhydride dose, 1ml/g, reaction time 22.97min, reaction temperature 85.9; for Potato starch dose acetic anhydride, 0.75ml/g, reaction time l5min, reaction temperature 70℃(2) For application reference, the in-depth analysis were made on pH, shear force and temperature impacts on the solution viscosity of corn acetate starch, potato acetate starch viscosity and transmittance of modified starch paste, freeze-thaw stability.(3) Electron microscopy (SEM) Scans revealed: shape of corn acetate starch powders was basically changed and remained almost round. Structure of starch granules were not devastated, only causing particle surface uneven. And shape of potato starch was not changed much also, is still oval. Structure of starch granules were not devastated either, only causing particle surface uneven. Bright spots showed some of them were may be eroded by alkaline.(4) Polarized light microscopy observation showed: For potato starch, polarization crosses located at the edge of the small particles obviously displayed vertical crossed; for potato acetate starch, reaction is almost the same to potato starch, but slightly impair to the edge. The results indicated esterification reaction of starch in starch granules of non-crystalline region, did not interrupt the crystallization of the ordered arrangement of starch chains.Polarized light microscopy observation showed: For corn starch, polarization crosses located at the edge of the small particles obviously displayed vertical crossed; for corn acetate starch, reaction is almost the same to potato starch, but slightly impair to the edge. The results indicated esterification reaction of starch in starch granules of non-crystalline region, did not interrupt the crystallization of the ordered arrangement of starch chains.(5) IR spectroscopy showed: corn starch acetate absorption peaks appear at 1724 cm-1,1373 cm-1,1246 cm-1, etc; potato starch acetate absorption peaks appear at 1761 cm-1,1376 cm-1,1242 cm-1 etc; it means acetyl could significantly effect starch molecules.(6) X-ray diffraction data revealed that potato starch is B-type crystalline structure, Esterification of potato starch mainly occurs in the amorphous zone does not occur in the crystalline region. The data of X-ray diffraction show that acetate starch diffraction peaks remain in 2θat 17.2°. It means that the aceticacid esterification occurred mainly in the amorphous areas of starch, did not occur in the crystalline region. Corn starch is a typical A-type crystalline structure, X-ray diffraction patterns of acetate starch in 20 were 15.0°,17.1°,17.9°and 23.1 v Department of diffraction peaks largely intact, the experiment showed, the acetic acid esterification occurred mainly in the amorphous areas of starch, not occurring in the crystalline region.(7) The two starch membrane-forming was comparative studied,Study of two starch membrane-forming, compared two kinds of properties of esterified starch membrane. The nature of the starch acetate membrane is improved.(8) Using starch membrane on peaches for preservation at room temperature, the experiment showed, starch membrane reduced the fruit rot ratio from 80% (with control fruits) to 50% after 20 days, reducing the change of water, vitamin c (VC), solubility solid content and total acid. Therefore, the coated starch acetate could significantly improved the preservation.