Process Of Partially And Extensively Hydrolyzed Casein And Analysis Of Allergenicity Of Hydrolyzed Products

Casein is the main protein in milk and the main substance that causes allergic reactions in infants and young children.Hydrolysis of large casein molecules into small peptides is the most common method for reducing allergenicity.At present,domestic and foreign researches believe that partial hydrolyzed protein ingredients require average molecular weight <5 k Da,and the content of peptides with molecular weight >6 k Da should not exceed 18%;extensively hydrolyzed protein ingredients require oligopeptides with molecular weight <3 k Da to contain at least 95%,and at least 3.5 k Da Only 1-5% above.Therefore,this study firstly took the degree of hydrolysis as the main measurement index,and finally determined the process of partial hydrolysis and extensive hydrolysis of casein through researches such as enzyme screening and hydrolysis condition control.Finally,the physicochemical indexes and sensitization of deeply hydrolyzed protein of two hydrolyzed raw materials,sodium caseinate and rennet casein,were deeply analyzed.Used sodium caseinate as raw material,we screened from pepsin,trypsin,chymotrypsin,papain,neutral protease and alkaline protease based on the degree of hydrolysis,electrophoresis and molecular weight distribution,and studied the preparation process of the partial hydrolysis and extensive hydrolysis of casein sodium.Papain was selected to partially hydrolyze sodium caseinate,the degree of hydrolysis was 9.2%,the molecular weight of more than 90% of the peptides was less than 6 k Da,and the molecular weight of about half of the oligopeptides was less than 1.2 k Da;The deep hydrolysis of sodium caseinate was achieved by the combination of alkaline protease and neutral protease.The degree of hydrolysis reached 20.78%.Among them,the molecular weight distribution of 99.59% casein hydrolyzate was below 3 k Da,and the molecular weight distribution of88.2% casein hydrolyzate was below 1 k Da.In order to regulate the hydrolysis process of sodium caseinate,and macroscopically achieve the purpose of obtaining hydrolyzed products with molecular weight and proportion,the structure is based on substrate concentration,enzyme-to-base ratio,hydrolysis time and hydrolysis degree.The hydrolysis kinetic model and the prediction statistics of the molecular weight of the hydrolyzate are very meaningful.The results showed that the kinetic equation of theoretical value and the actual value was verified,and the coincidence degree was high,which had practical significance.In the case of different hydrolysis conditions,one hydrolysis system corresponds to one kinetic equation and does not have universal adaptation.The value of the degree of hydrolysis can be obtained through the kinetic equation,and the degree of hydrolysis can be controlled by corresponding to the molecular weight distribution The value of the degree of hydrolysis can be obtained through the kinetic equation,and the degree of hydrolysis can be controlled by corresponding to the molecular weight distribution.Studies have shown that when the degree of hydrolysis was 1-10%,the molecular weight distribution of the hydrolyzate was mainly concentrated in 1-3 k Da;when the degree of hydrolysis was 11-20%,the molecular weight was mostly <1 k Da;when the degree of hydrolysis was greater than 20%,the hydrolysis was basically complete,the macromolecular protein was completely consumed,and the content of small peptides and free amino acids increases,which provides a reference for the control of other hydrolysis conditions.Reducing the allergenicity of casein is the ultimate goal of this study.In this study,on the basis that the molecular weight distribution meets the needs of the industry,different protein raw material sources(sodium caseinate and rennet casein)were simultaneously deeply hydrolyzed,and the sensitization detection and sensitization site analysis of the two hydrolyzates were determined.The results showed that there was no significant difference in the molecular weight distribution of the two raw materials after hydrolysis.However,in the case of different enzyme-to-substrate ratios of sodium caseinate,the allergy showed a phenomenon that first increased and then decreased,while the allergenicity of rennet casein was consistently decreased.After the LC-MS/MS determination of the two hydrolyzates,the enzyme has more cleavage sites for rennet casein,and the cleavage efficiency of allergic epitopes can reach more than 97%,which greatly reduces the allergy of casein.This paper provides a rationale for producing hypoallergenic dairy-based ingredients.