Enzymatic Production Of Xylose

Xylose (Xylose) is a five-carbon sugars, in nature, ainly in the D-xylose formation ofglycosaminoglycan present in the plant fiber hemicellulose within. Xylose is all functionalsugar in the nature of one of the most stable sugar. Xylose does not increase blood glucosevalue, to the proliferation of bifidobacteria have showed its superior function.At present, xylose production is mainly corn as raw material, using sulfuric acid at hightemperature and pressure conditions of hydrolysis. In addition to sulfuric acid method andalkali method outside, enzymatic method, in which the enzyme method because of the natureof specificity,decompose rapidly, mild condition, and the product quality, has become thefocus of the study.In this paper, using sugarcane bagasse as raw material to produce xylose, to obtain highyield of xylose as the goal, using a series of feasible scheme to improve the xylose yield, themain research contents and results are as follows：The use of steam blasting method for bagasse pretreatment, according to different stresscombinations and different time combination experiments. And then measure experiment rawmaterial of cellulose in residual volume, hemicellulose, lignin residue remaining amount.Through different experimental data found in contrast, when the pressure is3.0MP, time60s,the degradation of hemicellulose and cellulose and reached80%, hemicellulose degrade less.The use of steam explosion bagasse as raw material, using sulfuric acid to these rawmaterials for hydrolysis of a single factor experiment, orthogonal experiment and responsesurface experiment. Through the single factor experiments were acid concentration,hydrolysis time, ratio of solid to liquid three factors of the optimal conditions for the acidconcentration, hydrolysis time was0.3%1.5h, solid-liquid ratio1:8. According to the obtainedsingle factor experiment results, we conducted the experiment and response surfaceexperiment, to verify the single factor experiment, and through the response surface canobtain optimal value theory. The optimal value of the acid concentration of0.3369%,solid-liquid ratio is1:8.12, enzymolysis time1.8h conditions, hemicellulose decompositionrate can reach86.49%of the maximum. By high performance liquid chromatograpHyanalysis in the optimal condition, reducing sugar xylose accounts for66.57%. Compared with the traditional methods of yield was basically the same, but compared with the traditionalmethod it is obvious advantages.In this paper, second kinds of method of producing xylose is the use of xylanase directenzymatic hydrolysis of steam explosion bagasse raw materials for production of xylose. Thearticle first discusses the xylanase enzyme properties, then get the xylanase in the enzymatichydrolysis of sugarcane bagasse by single factor and orthogonal test results. Through theenzymatic properties of single factor experiment, the xylanase optimum condition, namely thepH value of5, a temperature of50℃condition of xylanase at the highest enzyme activity. Atthe same time the stability of xylanase in pH value of5, a temperature of50℃conditionsremained greater than50%8h enzyme activity. The xylanase optimum enzymatic conditions,conducted a xylanase enzyme after steam explosion bagasse raw materials by single factorand orthogonal experiment, finally, the enzyme concentration was2000U/g (raw materials),solid-liquid ratio of1:8, enzymolysis time of4h under conditions of enzyme the best solution.Through orthogonal test can obtain hemicellulose decomposition rate reached74.8%, whichaccounts for about54.52%of xylose solution. This method yields not acid high yield, and theenzyme specificity and bagasse structure.In order to obtain higher reducing sugar and xylose yield, we adopted the sulpHuric acidhydrolysis and xylanase enzyme combination method, namely acid enzyme method. Mainlydiscusses the enzymatic method for the single factor test and orthogonal test. We obtained inenzyme concentration was900U/g (raw materials), enzymatic hydrolysis time was3h,solid-liquid ratio of1:12, can get maximum xylose yield, while hemicellulose hydrolysis rate also isthe biggest. According to the final optimized conditions of hemicellulose decomposition ratesreached a maximum of97.2%. According to the HPLC analysis can be drawn, in enzymolysisliquid of xylose, accounted for89%of the total sugar, achieves the desired effect.