Study On Hydrolysis Of Wheat Gluten By Immobilised Protease

In order to improve the founctional property of wheat gluten, increase itsadditional value, and make its industrial production come true. The technics of preparingporous chitosan microsphere,immobilizing alkaline protease and hydrolyzing wheatgluten by immobilized alkaline protease were studied. The main results were as follows:1. The best conditions of preparing porous chitosan microsphereThe molecular weight of chitosan affects the external configuration observably, lowmolecular weight can make the operation easy and obtain prous chitosanmicrosphere.The concentration of chitosan and NaOH, ratio of ethyl acetate to NaOHand concreting time affect the whole shape of chitosan microsphere.The best conditions for preparing chitosan microspheres are as follows: the chitosanwith viscosity-average molecular weight of 448.4 KDa and concentration of 2.5％ascarrier, 3.0％NaOH as clotted solution, ratio of ethyl acetate and NaOH solution is 5％,agglomerating for 3h. It can be used as carrier to immobilize protease in theory.2. Select the best protease for immobilizingThrough the orthogonal test,, alkali protease was chosen for immobilizing tohydrolyze wheat gluten.3. The best conditions of immobilizing alkali proteaseThe concentration of alkali protease has obvious effect on the immobilization ofalkaline protease. The recycling rate of activity is increasing with the augment of enzymeconcentration. Absorption and cross bonding time, the concentrations of glutaricdialdehyde and BSA affect the immobilization of alkaline obviously. So they are must becontrolled to a proper area.The optimum conditions for preparing prous chitosan microspheres are as follows:the ratio of alkali protease to porous chitosan microsphere is 315U/g, the concentrationof alkali protease is 45mg/mL, immobilizing temperature and pH are 4℃and 7.2,absorption and cross bonding time are 48h,and 8h respectively., the concentration ofglutaric dialdehyde and BSA are 1.0％(final concentration) and 4.5mg/mL respectively.The recycling rate of activity achieved 66.52％.4. The physical and chemical property of dissociative and immobilized alkaliproteaseThe optimum temperature and pH of immobilized alkali protease are a little higherthan that of dissociative alkali protease, and its thermal, pH and store stability improveobviously. 5. The technics of immobilized alkaline protease hydrolyzing wheat glutenThe results of orthogonal test indicates that the optimum conditions for hydrolyzingwheat gluten by immobilized alkali protease are as follows: the wheat glutenconcentration of 2.5％, immobilized alkali protease concentration of 4000U/g,hydrolyzing for 3h, the degree of hydrolysis reaches 9.5％which is almost the same asthat of dissociative alkali protease.6. The function property of different wheat gluten unhydrolyzed, hydrolyzed bydissociative and immobilized alkali proteaseThe solubility of wheat gluten hydrolyzed by dissociative and immobilized alkaliprotease increase obviously, the emulsifying property and emulsion stability increaselightly, foaming tendency declines and foam stability is almost the same as the wheatgluten unhydrolyzed.7. The operation stability of immobilized alkaline proteaseThe immobilized alkaline protease can be operated stably and its activity is veryhigh all the time after hydrolyzing wheat gluten continuously for 6 times, the degree ofhydrolysis is retaining about 9％. It is possible to use the immobilized alkali protease inthe industrial production of wheat gluten's modification.