The Research Of The Technology Of Enzymic Combined Oxidation Pretreatment To Prepare Chitooligosaccharide

Do research of the technology of degradation chitosan,Through those process,gain a method of prepare chitosan oligosaccharide with molecular weight at 500-2000.chitosan with high molecular weight was pretreated by hydrogen dioxide and became water-soluable.Than usingα-amylase to degradate chitosan to prepare functional chitosan oligosaccharide,the production can separated by alcohol precipitated.And than,we also studied the technology of oxidation method to prepare chitosan oligosaccharide by hydrogen dioxide.The results are as follows:①First,The optimum conditions for preparation of water-soluble chitosan by hydrogen dioxide are as follows:the temperature is 60℃,the time is 0.25h,the concentration of hydrogen dioxide is 0.3%,the concentration of chitosan is 3.0%.Removing the remaining hydrogen dioxide by rotary evaporation under low temperature,we obtained the water-soluble chitosan with Mn5000,the colour of it is light green. ②Second,we have obtained the best conditions ofα-amylase degradation chitosan:temperature is 60℃,pH6.0,ratio between liquid and solid(V/W) is 5:1,enzyme quantity is 40U/g,enzymolysis time is 180mins.we obtained the chitosan oligosaccharide with degree of polymer (DP)3.2 hydrolysis under such condition.We can control the DP of chitosan oligosaccharide through adjusting enzyme quantity and enzymolysis time,than we obtained the chitosan oligosaccharide with DP 5.4.The production that separated though precipitated by two volume of alcohol are mainly comprised of 2 to 12 chitosan oligosaccharide.It was proved by electro-spray ionization mass spectromotry(ESI-MS) analysis.③At last,the optimum conditions for preparation of chitosan oligosaccharide by hydrogen dioxide are as follows:the concentration of acetic acid is 1.0%,the temperature is 60℃,the concentration of hydrogen dioxide is 1.0%,the concentration of chitosan is 3.5%,the time are 4.5h and the speed of shaking table is 150rpm.We obtained the chitosan oligosaccharide with DP4.3.The production that separated though precipitated by alcohol are mainly comprised of 1 to 4 chitosan oligosaccharide.It was proved by ESI-MS analysis.We can found that the main production of enzymic degradation and chemical degradation are different,the first is chitosan oligosaccharide,the second is monosaccharide;the remaining hydrogen dioxide in chitosan oligosaccharide solution can make error to Reducing end method measure molecule weight.