Study On Recrystallization Orderliness Of Amylopectin Under Different Debranching Conditions

Amylopectin recrystallization deposit and supernatant were prepared by using pullulanase to prepare amylopectin through different time(2 h,12 h,24 h)then at different temperature(4?,25?,30?,40?)to accomplish recrystallization and centrifugal separation.Saccharometer,Scanning electron microscopy(SEM),Particle size distribution instrument,X-ray diffractometer(XRD),Infrared spectroscopy(IR),High performance liquid chromatography(HPLC)and Thermogravimetric analysis(TGA)were used to analyze sugar content of the soluble,particle morphology and size,crystal structure,intramolecular and intermolecular interaction of chemical bonds,molecular distribution,thermal properties in the solution during recrystallization.These were characterized in order to investigate the effect of debraching time and recrystallization temperature on the recrystallization characteristics and the regularity of recrystallization according to these information.(1)Through recrystallization of amylopectin at different temperature,it was found that the flocculation rate was fast and the deposit yield was high at low temperature(4?).(2)The soluble sugar in the supernatant of amylopectin was involved in the flocculation of the precipitated crystal with the recrystallization,and the initial sugar content in the solution was high after 12 h,but almost all of them were involved in the flocculation of the deposit after recrystallization.At different recrystallization temperature,the consumption rate of soluble sugar in the supernatant decreased with the increase of temperature.(3)The supernatant for 2 h was a lamellar structure composed of many small particles.The supernatant of 12 h and 24 h was still smooth and flake under high power microscope,while the precipitate crystal pore of 2 h was larger,and the structure became more compact and compacted with the prolongation of the debrachling time.The microspheres in the structure were smaller.The recrystallization deposit particles reached the level of several hundred nanometers at decolorization for 12 h,reaching about 250 nm.At 4?,the supernatant had smooth surface and a small amount of round rod,and the temperature rise was formed by a uniform shape of circular particles.However,the precipitated particles at different temperature are small grains with little difference in size,and with the temperature rising to 40?,the particles were close to microspheres.Compared with the original starch,the deposit crystal of amylopectin debranched and recrystallized had smaller particle size but worse homogeneity.At 4? for 12 h,the deposit size was the smallest,the dispersion was the smallest,and the uniformity of the particles was the best.(4)The amylopectin was debranched to produce small molecules,and more molecularweight starch molecules were produced by different ways and degrees of self-assembly.There was a single polysaccharide in the supernatant solution after recrystallization at 4 ? and 40?.(5)The debranched recrystallized starch precipitates were characterized by partial ordered crystal structure,and the relative crystallinity increaseed with the prolongation of the descaling time,and the enthalpy value increaseed gradually,and the most orderly structure was obtained at 24 h.The supernatant lost the crystallinity of starch at 4? at low temperature,and the crystallinity increased to 40? at room temperature.The crystalline form became B+V,and the enthalpy reached 42.29 J/g.IR analysis showed that the structure order of precipitate increased with the increase of temperature,which coincided with the results of XRD.(6)Thermogravimetric analysis showed that the maximum rate degradation temperature of recrystallization supernatant at 4? was the smallest and the most easily decomposed.The maximum rate of deposit degradation temperature decreased with the increase of crystallization temperature,while the supernatant increased with the increase of crystallization temperature.By studying the effects of debraching time and recrystallization temperature on recrystallization characteristics,some rules of recrystallization of amylopectin were found out.It provides a theoretical basis for studying the ideal products of amylopectin recrystallization and starch composites.