Application Of α-Dextranase In Sugarcane Mill And Characteristic Research Of The Enzymolysis System

Application of dextranase and complex enzymes to hydrolyze dextran and otherpolysaccharose in sugarcane mills was studied in this paper. In addition, GPC, IC, FTIR,13CNMR and HAAKE were employed to represent the characteristics of dextran enzymolysissystem. Specific research described as follows:1. The application of dextranase in sugarcane mixture clarification was studied. Firstly,the content of dextran and filtration rate etc. of sugarcane mixture reststanding in the naturalenvironment were determined. Then on the basis of single factor experiments, theoptimization of dextranase to hydrolyze dextran in sugarcane mixture was carried out byresponse surface methodology （RSM）. Considering practice manufacturing process in sugarmills, the optimum operational conditions were suggested as follows: enzyme dosage10-15mg/kg, pH5.0-6.0, temperature50-65℃, and reaction tim e10-15min. Finally, aconfirmatory experiment was conducted in the optimal condition by simulating practicalmixture processing: adding10mg/kg dextranase in the clarified juice, dextran removed61.32%, settling time was cut down13.46%, purity raised0.65%，while pH and Brix had noobvious changes. Besides,we chose the place of adding imbibition water to be the place ofadding dextranase.2. According to single factor experiments together with practice manufacturing process,experiments were conducted on pectinase and amylase enzymolysis, and got the optimalcondition. Synthesizing the three enzymes, ensure the total amount of the three enzymes to be10mg/kg. Orthogonal experiment was adopted to determine the influence for viscosity ofmixture, with proportion of the three enzymes, pH and temperature to be factors. Theoptimum operational conditions were: dextranase: pectinase: amylase6.3:2.7:1or4.2:1.8:4,temperature55-65℃, pH5.0-5.5. the viscosity of mixture decreased by47.1%in thiscondition. we still chose the place of adding imbibition water to be the place of addingcompound enzymes.3. The changing regularity of dextran molecular weight and concentration inenzymolysis process was detected by GPC. After reststanding in natural environment for20hours, the molecular weight of dextran in mixture distributed in two areas:1.02×10⁶Da and 3.57×10³Da. Dextran T-2000and dextran in mixture were both used to be experimentalized.As the reaction time extended, the molecular weight of dextran dropped significantly, but itwas hardly for dextran to be degraded completely to monose in5hours, which presumed that,the determine result of using enzyme hydrolysis to determine dextran concentration could beundervalued. This conclusion can be further tested by IC. The changing regularity of dextranconcentration was directly bound up with dextran molecular series. FTIR and¹³C NMR wereused to determine the enzymolysis process in constructure, verifying that the enzymolysis wasa process to cut down α-（1â†'6） glycoside bond, having no impact on the branch.4. HAAKE was used to study the rheology of dextran solution and mixture. In differentconcentration, molecular weight, pH and temperature. they were finally verifed to benonNewtonian pseudoplastic fluid, and had a little thixotropy. In addition, it also studied thedynamic viscoelasticity of dextran solution, and the results showed that, for all differentconcentration and molecular weight of dextran, both the elastic modulus G′and the viscousmodulus G′′increased along with oscillation frequency increase, and G′increased faster.While in different temperature, the changing of both G′and G′′was not significant. In thewhole oscillation frequency range, dextran solution showed up dynamic viscoelasticity.