Study On Production Of Functional Oligosaccharides By Enzymatic Hydrolysis In Cornhusk

Cornhusk is the cellulosic residue of starch producing. In this article, cornhusk was hydrolyzed into xylo-oligosaccharide and cello-oligosaccharide with xylanase and celluiase individually. The research work had important academic, social and economic value.The yield of hemicelloluse extraction was 85%, under the conditions of 40℃, NaOH concentration 2%, solid-to-liquid ratio 1:10, extracting time 24h. The alkaline pretreatment of cornhusk had the virtues of mild-conditions, low-energy-consuming, meanwhile it didn't destroy cellulose and hemicellulose. So it would be benefit for preparing oligosaccharides with enzyme.The xylanase characters and enzymatic hydrolysis course were well studied. The optimal conditions were 50℃,pH4.8, xylanase dosage 50IU/g substrate, substrate concentrations.0% and reaction time 2h. The degree of polymerization(DP) of product was2.26 under the optimal conditions.Adsorption characteristics of celluiase on 5%cornhusk were investigated at pH4.8, 50℃, the result showed that endo-|3-l,4-glucanase(CMC) and exo-P-l,4-glucanase(C1) were mainly absorbed in the substrate, but cellobiase(CB) was mostly maintained in the liquid phase. It was helpful to master the catalysis mechanism of celluiase and optimize the cellulose hydrolysis.It was good for increasing the rate of cello-oligosaccharide in the product and DP of product to removing cellobiase during the course of celluiase hydrolysis. At the optimal conditions of 50 ℃ ,pH 4.8,substrate concentration 5 % , celluiase dosage 7.5FPIU/g substrate, enzymatic hydrolysis time 6h, the yield of cello-oligosaccharide was 77% and DP of product was3.44. Later, the glucose rate in the product increased whereas the yield of cello-oligosaccharide decreasedBased on the adsorption characters of celluiase, the method of a fed-batch enzymatic hydrolysis was set up. The enzymatic hydrolysis reaction was proceeding for 6h following the above conditions, then the fresh cellulosic residue was added into the reaction system after filtrating and the hydrolysis continued for 10h. By this way , CB was removed, meanwhile C1 and CMC were reutilized repeatedly.The results of scale up test showed that, 15.2kg cello-oligosaccharide and 21.1kg xylo-oligosaccharide were produced from 100kg cornhusk, the oligosaccharide yield from cornhusk was 32.7%. Both social and economic profit would be good.