Research On The Change Of Allergic Protein During The Surimi Fermentation And Its Reason

Fish is one of the eight major allergens.As one of the important protein for Chinese,freshwater fish allergies cannot be ignored.Previous studies have confirmed that fermentation technology can effectively reduce the allergenicity of milk,wheat,legumes,and other protein foods,but the effect of fermentation on fish is still not clear.This research was conducted mainly to investigate the allergenicity of main freshwater fish in China and whether fermentation by strains can effectively reduce the allergenicity of freshwater fish.This thesis could provide a theoretical basis for developing hypoallergenic freshwater fish products and expanding the freshwater fish processing industry.First of all,seven freshwater fish species were studied.The difference in their protein composition was detected by SDS-PAGE,and the binding of the sarcoplasmic proteins from seven freshwater fish species to 20 positive serum of fish allergy patients and 1 negative sera was detected by indirect ELIS Ato compare the allergenicity of the seven freshwater fish species.After purification of the parvalbumin,Matrix-Assisted Laser Desorption/Ionization Time of Flight/Time of Flight Mass Spectrometry(MALDI-TOF/TOF)was used to identify the purified extraction.The results of IgE binding capacity of freshwater fish sarcoplasmic protein showed that the allergenicity of Chinese main freshwater fishes were as follows:black carp(ODaverage=0.821)>grass carp(ODaverage=0.575)>chup(ODaverage=0.553)>bighead(ODaverage=0.455)>bream(ODaverage=0.453)>crucian(ODaverage=0.352)>carp(ODaverage=0.311).59 mg of purified protein,which was identified as parvalbumin,were effectively separated by 60%-100%ammonium sulfate salting out,DEAE-Sepharose column,and Sephacryl S-200 HR gel column from 100 g of the white meat from black carp back and it could be used in the research of mechanism.Then black carp was then chosen for further study due to its highest allergenicity.The pH,SDS-PAGE,western blotting,and indirect ELISA of different fermentation conditions used in fermentation were measured to confirm the effect of fermentation on the immunological properties of black carp allergens.The results showed that,compared with Staphylococcus xylosus and Saccharomyces cerevisiae,Lactobacillus plantarum had the strongest acid-producing ability.After fermentation with Lactobacillus plantarum,the pH of the fish was 4.51 and the IgG and IgE binding reduction rate of sarcoplasmic protein reached the maximum,33.12%and 75.27%,respectively.The IgG binding reduction rate of sarcoplasmic protein was 39.71%and the maximum reduction rate of IgE binding capacity was 76.13%at 60 h.With an incubation concentration at 1.5%,the allergenicity of sarcoplasmic protein was the lowest.During the fermentation process,changes in NaCl content affected the immunological properties of fish allergens(p<0.05),while changes in glucose content had little effect(p>0.05).According to the key fermentation conditions,an acid production simulation system,ionic strength simulation system,and enzyme production simulation system were established.Besides measuring the changes of allergenicity,the surface hydrophobicity,endogenous fluorescence value,and circular dichroism spectrum were measured to analyze the structure of sarcoplasmic protein and parvalbumin.The allergenicity of proteins under low pH conditions was slightly reduced.For parvalbumin and sarcoplasmic proteins,the α-helix content of the secondary structure was lower,and the irregular curl content increased.The surface hydrophobicity increased,and more tryptophan hydrophobic groups of sarcoplasmic proteins was exposed to a polar environment.Ionic strength ranged from 0.0 to 1.0 had no significant effect on IgG/IgE binding capacity.When the ionic strength of parvalbumin and sarcoplasmic proteins was 0.0,the α-helix content was high,the surface hydrophobicity was significantly reduced,the tryptophan residue of sarcoplasmic proteins was exposed to a polar environment,and there was no significant difference between the groups with ionic strength higher than 0.2.Microbial enzymes,endogenous enzymes had a greater impact on the reduction of protein allergenicity,of which acidic endogenous enzymes played a major role.The decrease in the allergenicity of allergenic proteins was mainly due to the reduction of the α-helix of the secondary structure,which destroyed the conformational epitopes of the allergenic proteins,resulting in a decrease in the allergenicity of freshwater fish during fermentation.