Effect Of Soy Protein On The Heat-induced Aggregation Behavior And Gel Properties Of Cod Protein

Gelatability is one of the most prominent functional properties of soybean protein,providing elasticity,hardness,water holding capacity,flavor retention and other functions for the food system.Cod is a common and affordable fish with high protein content,rich nutrition,complete amino acids,making them valuable food to highly developed and utilized.The understanding of the gel structure and the relationship between the gel structure and properties are of theoretical significance to the exploration of the mixed gel properties of soybean protein and cod protein.The effects of the proportion of soybean protein(SP)and cod protein(CP)in the mixed system(5:0,3:1,1:1,1:3,0:5)on the physical and chemical physicochemical properties,aggregation behavior,energy storage modulus and microstructure of the heat-induced protein gel were studied.The results showed that with the increase of cod protein ratio,the surface hydrophobicity and the number of disulfide bonds of the protein mixture after heat treatment were significantly increased.Additionally,The results of afm showed that when CP ratio increased from 0 to 100%,the particle size of thermally-induced protein aggregates increased significantly.The results of diagonal electrophoresis showed that the larger aggregates in the thermally induced mixed protein were mainly composed of cod actin and soybean basic polypeptide.Reduction of sds-page showed that the non-network proteins in the gel were mainly composed of soybean 11 S globulin acid(A)peptide chain and cod tropomyosin.In addition,as the CP ratio increased from 0 to 100%,the proportion of non-network proteins in the gel network decreased significantly from 12.5% to 3.2%.The results of sem and rheometer showed that the gel with high CP ratio has higher energy storage modulus and larger pore size.the fact that soybean protein and cod protein would formed thermally-induced gel respectively,instead of interacting with each other during the heating process was confirmed by Fluorescence spectrum and circular dichroism spectrum data.In this study,the effects of 7S/11 S ratio(5:0,3:1,1:1,1:3 and 0:5)and preheating conditions(temperature and concentration)on the aggregation behavior and gel properties of mixed proteins were further investigated.When the ratio of 11 S protein was increased,the surface hydrophobicity of the mixed protein increased and the number of disulfide bonds increased.Particle size and exclusion chromatographic data showed that the size of the mixed protein aggregates increased with the increase of 11 S protein.The results of scanning electron microscope and rheometer showed that with the increase of 11 S ratio,the energy storage modulus of the mixed protein gel increased,and the pore size and inhomogeneity of the microstructure of the gel increased.By studying the effects of preheated soybean protein on the mixed protein system,it was found that increasing the preheated temperature or protein concentration could increase the degree of thermal aggregation of the protein mixture after heat treatment,and increase the elastic modulus of the mixed protein gel system.