Study On Enzymatic Separation And Preparation Of Wheat Gluten

Wheat gluten is also called active gluten powder, which is a kind of high gradecereal protein. At present, Wheat gluten is separated from wheat flour by addingplenty of water, then repeatedly washing the dough. This process consumes a largeamount of water, also produces a large amount of wasted water, the whole processneeds high energy. It is always one of the hot research topics that looking for asmall water consumption and a more economical and efficient method for theseparation of wheat gluten.Recently, enzyme hydrolysis technology is a kind of new technology widelyused in food industry and is very useful for the separation of grain protein such asrice protein and soybean protein, but enzymatic hydrolysis technology hasn’t beenused for the separation of wheat gluten. Based on this condition, the wheat glutenwas separated from wheat flour by enzymatic hydrolysis technology.Processingparameters, enzymatic hydrolysis mechanism, ultrafiltration purification and theeffect of the different drying conditions on functional properties of wheat glutenprotein were researched. The results will be refered as a new method for theseparation of wheat gluten, the main researching contents are as follows:(1) On the basis of single factor experiment, optimization of extraction of wheat glutenprocessing parameters by response surface design using Design-Expert7.1.6and amathematical model established to predict the optimal processing parameters were studied.The result showed that the purity of wheat gluten was forecast to80.28%at the conditionof enzyme dosage2.58%, hydrolysis temperature58℃, pH5.94, reaction time4.0h.However, considered the actual situation of the convenience and cost, the corrected datawere enzyme dosage2.5%, hydrolysis temperature55℃, pH6, reaction time4h, thepurity and the yield of wheat gluten at this condition was77.57%and76.70%,respectively. It indicated that this model was more accurate.(2) Basedon the above-mentioned results, substrate concentration, enzyme concentration,pH and temperature on hydrolysis rate of wheat flour with α-amylase were studied. TheMichealis constant (Km) and maximum rate (vm) were deduced by comparingLineweaver-Burk plot and Wilkinson statistical method. Results indicated that, in theoptimal condition of pH6.0and temperature60℃, Kmand Vmwere2.940mg/mL and0.348mg/mL·min, respectively. Michaelis-Menten equation was and the predicted results were consistent with the measured values in the demonstration test. In the condition of temperature30-60℃, enzymatic kinetic equation was(3)Enzymatic hydrolysate was used as processing material in ultrafiltration experiment. The effect of pressure, pH, ratio of solid to liquid and temperature on protein retention rate,the total sugar concentration and membrane flux were studied by orthogonal test, the optimal conditions were pressure0.25MPa, pH6.0, the ratio of solid to liquid3%, temperature25℃. The results from the validation experiments showed that the actual gluten purity was83.23%. A mass transfer equation J=17.9471nCb+44.851was developed to reveal the mechanism of mass transfer in ultrafiltration. When ultrafiltration concentration was12.17%, the membrane flux became small, it had no great effect on ultrafiltration if it continued to increase fluid concentration.(4) The wet gluten after ultrafiltration was dried by three kinds of methods such as hot air drying, vacuum drying and freeze drying, the emulsifying ability and emulsifying stability, foaming ability and foaming stability, solubility of wheat gluten were comparated with the commercial wheat gluten. The results showed that, the emulsifying ability and emulsifying stability of wheat gluten from freeze drying and from hot air drying was64.32%and60.43%,38.35%and48.32%, respectively. Foaming ability and foaming stability of wheat gluten from vacuum drying and from hot air drying was65.37%and63.25%,48.45%and56.23%, respectively. Solubility from above three kinds of methods was similar. The properties of wheat gluten from vacuum drying were also superior to the commercial wheat gluten, and the vacuum drying was a good drying method.