| In meat processing,the physical and chemical properties of muscle proteins(including gel properties,emulsifying,hydration,solubility,meat particle adhesion and fiber swelling)determine the quality of meat products and affect consumer satisfaction.Myofibrillar proteins(MP),as the main component of pork protein,plays an important role in the texture and water retention of meat products.Muscle protein oxidation will affect the functional properties of the protein.Excessive oxidation can lead to a reduction in protein functional properties and a reduction in meat product quality.Therefore,this article takes MP as the research object,by establishing two hydroxyl radical simulated oxidation systems,namely chemically oxidized Fenton-H2O2 and enzyme oxidized GluOx-H2O2,to study the effects of different oxidation levelss on MP structure,emulsifying and gel properties To explore the differential effects of different oxidation methods and concentrations on the levels of protein oxidation,in order to choose a reasonable and controllable oxidation modification method to improve the functional characteristics of MP,and lay the foundation for the application in gel meat products.The main research results are as follows:First,MP was used as the research object to establish a hydroxyl radical oxidation system to study the effects of two oxidation modes and different oxidation levelss on the physical and chemical properties and structure of proteins.The research results showed that with the increase of H2O2 concentration,the two oxidation methods will increase the protein carbonyl content,the reduction of the sulfhydryl content is converted into disulfide bonds,the surface hydrophobicity first increases and then decreases,and comparing the two oxidation methods found that the enzyme oxidation(GluOx),the hydrophobicity of the surface changes more obviously(P<0.05).The results of SDS-PAGE showed that the oxidized protein was cross-linked,and the disulfide bond was the main covalent bond involved in the cross-linking.Comparing the two oxidation methods,SDS-PAGE showed that more cross-linking of the protein involved in the GluOx oxidation.The above results indicated that there are differences between the two oxidation methods resulting in different levelss of protein structure changes.Then the effects of two oxidation modes and oxidation concentrations on the properties of the protein emulsion are studied.The research results showed that the emulsifying activity and emulsifying stability of protein emulsions showed a trend of increasing first and then decreasing.Observing the micro structure of the emulsion showed that as the concentration of H2O2 increases,the emulsion droplets decrease first and then gradually increase The droplet size of the emulsion was found under different oxidation methods.When the concentration of H2O2 in Fenton oxidation is 1 mM,the droplet diameter is the smallest and the distribution is relatively uniform,while in the GluOx oxidation method the glucose concentration is 2 mg/mL.The disulfide bonds formed during the oxidation of the protein will cause the aggregation of fat globules to prevent the flow of the emulsion droplets.Under the two oxidation methods,as the shear force increases,the apparent viscosity continues to decline,showing shear thinning behavior,Under the action of the same shear force,the apparent viscosity curve of GluOx oxidation method is more dispersed.The dynamic rheological results showed that as the frequency increases,the storage modulus(G')showed an upward trend and is higher than the loss modulus(G").Comparing the two oxidation methods,it can be found that the emulsion system after GluOx oxidation is more stable.The above results indicated that the GluOx oxidation method is more beneficial to improve the emulsifying properties of protein emulsions at the same oxidation concentration.Finally,the effects of two oxidation methods and different oxidation concentrations on the properties of protein gels were studied.The results showd that when the concentration of H2O2 is low(less than 3mM),the fat particles are small and the interface protein membrane is intact.With the further deepening of the oxidation levels,the interface membrane ruptures and the fat globules are released,especially when H2O2 is 10 mM.The interface film is completely destroyed.The hardness,elasticity,chewability and cohesiveness of protein gels show a tendency to increase first and then decrease.The difference in the texture of the gel caused by the difference in oxidation methods was different.The strength and elasticity of GluOx oxidation gel are all in glucose The concentration is maximum at 2 mg/mL,and Fenton oxidation is maximum when H2O2 is 1 mM.The water holding capacity corresponding to gel hardness and elasticity also showed the same trends.According to the rheological test results,under the same oxidation levels,the storage modulus(G')of GluOx oxidation method was higher than that of Fenton oxidation,and it was easier to form a dense gel network structure.Analysis of the moisture distribution of the gel showed that,compared with Fenton oxidation,the water movement in the protein gel after GluOx oxidation is weaker and the water holding capacity is better.In summary,the influence of protein structure and functional properties is not only related to the levels of oxidation,but also to the way of oxidation.Oxidation will change the structure of the protein,but the levels of influence caused by the difference in oxidation methods is different.At low concentration oxidation,both oxidation methods are beneficial to improve the emulsification and gel properties of the protein.As the oxidation concentration is further increased,the two Each oxidation method will make the protein emulsifying and gel properties worse.Compared with Fenton oxidation,the emulsifying and gel properties of GluOx oxidized proteins are less degraded... |
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