Characterization Of Aggregation And Immunological Evaluation Of Modified Wheat Protein With Stronger Deamidation

Wheat is one of the most important staple foods in the world.However,its utilization can not be access to some allergic people due to its harmful immune responses.Wheat protein deamidated by edible organic acid is a relatively safe and economical method in the field of protein modification.Significant differences in domain value and effect for the effective desensitization of wheat protein are the main controversial issues.Therefore,it is urgent to perform a high degree of deamidation(DD>80%)for food precessing in order to detoxify wheat protein.In this paper,the method of the high deamidated wheat protein was obtained by optimizing the modification conditions in the low-original aggregation system upon hydrothermal treatment.Different degree of deamidation was achieved by controlling original aggregation state of wheat protein from dilute to concentrated regimes.The effects of modified wheat protein from high deamidation to low deamidation on changes of aggregation state and immunological effect were explored.The immune differences of’gliadin in long-time fermented sourdough with different lactic acid bacteria and high deamidated wheat protein were compared,and the study evaluated the ability of desensitization of wheat protein with stronger deamidation.The texture and water relaxation characteristics of the reconstituted dough with different degree of deamidation were investigated.The main contents and results are as follows:(1)On the basis of single-factor test,the processing parameters.including the concentration of wheat protein,the concentration of citric acid and the deamidation time,were optimized by the surface response methodology.The degree of deamidation of 92.2%was obtained at the optimal conditions of concentration of wheat protein 7 g/L,the concentration of citric acid 6%,the deamidation time 12 min.(2)The original aggregation state of wheat protein was regulated to explore the relationship between the conformation change and the immune ability of the high deamidated wheat gluten protein(DD=92.2%).Based on the analysis of Zeta potential,SDS-PAGE,FTIR,endogenous fluorescence and ELISA,the protein conformation were unfolded and exposed a large amount of the amide groups(Gin&Asn)to react with H+,increasing the degree of deamidation,which reduced the number of immunogenic epitopes in contact with the gliadin immunoglobulin antibody.The antigenicity of the high deamidated wheat protein xwas reduced by about 72%(p<0.05)compared with the positive control.(3)Gliadin at higher deamidation(DD>90%)could effectively reduce the number of toxic peptides and decrease the risk of wheat contamination for coeliac patients by comparing gliadin obtained by long-term fermentation with Lcactobacillus plantarumB02012 and Lactobacillus alimentarius20998.Furthermore,the Lactobacillus plantarumB02012 had a slight desensitization,whereas Lactobacillus alimentarius20998 caused sensitization instead.(4)Study on the texture,moisture state and the network structure of the reconstituted dough with different degree of deamidation could be concluded as follows:the adhesiveness and ductility of the recombinant dough(WG-7)were significantly improved compared with the dough of lower deamidation degree(CK,WG-30,WG-100),elasticity of doughs remained unchanged,and the cohesiveness,chewiness,cohesiveness,tensile force,the relaxation time T21 and semi-bound water S22 of the WG-7 were reduced,the content of bound water S21 increased significantly.These results further illuminated that higher deamidation(DD>90%)could better regulate the dough’s mechanical properties by improving the dough’s interaction with water and increasing the capacity of holding water.