Hydrolysis Of Corn Gluten Meal And Its Application

Corn gluten meal(CGM),containing 40～60%protein,is the main by-product in the extraction of starch from corn.Because of its poor dissolvability,coarse-feeling and, moreover,lacking human body essential amino acids such as lysine and tryptophan,CGM was now mainly used as animal feed or just treated as a waste,only a few of it has found use in the food industry of mankind.The enzymolysis of CGM can be a very important approach for recycling CGM because it transforms the proteins into amino acids and oligopeptides.In this study,the optimum of the hydrolysis conditions for the acidic protease excreted by Aspergillus niger by the response surface method,the enzyme activity change during the hydrolysis of CGM and its causes,and the use of the hydrolyte for the synthesis of zeolite ZSM-5 have been studied.The following results are obtained:First,the optimized CGM enzymolysis conditions for the acidic protease excreted by Aspergillus niger given by the response surface method are specified by substrate concentration 100 g/L,hydrolysis temperature 55℃,acidic protease dosage 12%(based CGM substrate),hydrolysis time5 h.Under such conditions a HD value(hydrolysis degree)of 35%is forecasted,which agrees with the experimental value(34.84%)very well.This means that the response surface method is suitable for use in the hydrolysis of CGM.Second,the investigation of acidic protease activity change in the process of CGM hydrolysis was performed under the conditions of substrate concentration 100 g/L,acidic protease dosage 12%,and hydrolysis temperature 55℃.Results show that the hydrolysis of CGM substrate by acidic protease was characterized by fast increases of the degradation rate of the solid CGM and the hydrolysis degree of the proteins in the beginning period,slow increases in the middle period(ca.8 h after start),and no increases in the later period.The deactivation of the enzyme is considered to be the cause of the hydrolysis behavior.From parallel experiments it is concluded that two deactivation manners of the enzyme,i.e.,the product-inhibition and the enzyme denaturalization,occur during the hydrolysis of CGM.Third,ZSM-5 zeolite was synthesized hydrothermally by using CGM hydrolyte as additive.It is found that the hydrolyte of CGM has an obvious function of adjusting the morphology of the zeolite.