Research On The Effect Of Myofibrillar Protein Oxidation In Ham By Nitrosation

Meat is the main source of the human animal protein,the nutritional value of meat is the main protein,fat and also provide some vita mins and minerals,so the meat is indispensable in the human diet.Meat protein is the most sensitive to oxidation,myosin,followed by troponin.The characteristics of meat processing and storage in the process of protein oxidation is a conformational change,aggregation,solubility and functional properties were generally lower,all of these are the quality of the final product has a negative impact.Thus,the oxidation of proteins and lipids to a minimum,which is very important in commercialization.It is the most effective way to add antioxidants in meat products.In a variety of foods in the antioxidant role in the processing and storage process,the addition of phenolic substances,can inhibit the oxidation of oil and protein.The ability of plant extracts to inhibit oxidation seems to be more pronounced than inhibition of protein oxidation and inhibition of lipid oxidation.Natural antioxidants extracted from plants have the benefits of free radicals and are good for human health.The purpose of this study was to deter mine the effects of different doses of phenolic antioxidants(EGCG)on the properties of myofibrillar protein emulsion gels,and to elucidate the mechanism by which phenolic antioxidants destroy the two sulfur bond network structure.Follows are the contents and results:1.EGCG on the properties of myofibrillar emulsion gel: the extraction of myofibrillar protein in pork,oxidative treatment and the addition of different doses of EGCG,using DSC to deter mine the thermodynamic properties of myofibrillar protein solution.Then the myofibrillar protein solution was mixed with soybean oil to form an emulsification system homogenized.The rheological properties of the protein emulsification system were measured by rheometer.After heat induction was induced into myosin fibrin gel,The distribution of lipid particles in emulsified gel was deter mined by laser confocal technique.The texture characteristics of emulsified gel were analyzed by texture analyzer.The emulsion gel was analyzed by scanning electron microscopy(SEM)of the microstructure.2.The mechanism of EGCG and mercapto addition reaction on the properties of myofibrillar emulsion gel: evaluate the disulfide bond force in protein emulsified gel;spectrophotometric deter mination of total sulfhydryl content in myofibrillar protein;The electrophoretic pattern of myofibrillar protein was analyzed by non-reducing SDS-PAGE,which revealed the mechanism of myofibrillar protein and EGCG covalent effect on the properties of myofibrillar emulsion gel.3."Thiol-quinone" addition reaction and regulation mechanism of influence on the gel properties of myofibrillar protein emulsifying: extraction of pork myofibrillar protein,strength of oxidative stress(H2O2 concentration),reaction temperature,ionic strength(NaCl concentration)and pH value of reaction system between the EGCG and the myofibrillar protein thiol addition reaction and the effect of protein in the emulsion coagulation characteristics.The processing of myofibrillar protein solution and protein emulsion gel after combined treatment of various conditions,through the analysis of the conditions of combined protein emulsion gel water retention,oily,microstructure,texture and rheological properties,and analysis of the various conditions of combination of myofibrillar protein thiol content,two disulfide bond content,electrophoresis,"sulfhydryl" addition product content and site effects,effects of EGCG on gel properties of myofibrillar protein emulsifying.The dose-dependent effects of(-)-epigallocatechin-3-gallate(EGCG;0,100,or 1000 ppm)on the textural properties and stability of a myofibrillar protein(MP)emulsion gel were investigated.Addition of EGCG significantly inhibited formation of carbonyl but promoted the loss of both thiol and free a mine groups.Addition of EGCG,particularly at 1000 ppm,initiated irreversible protein modifications,as evidenced by surface hydrophobicity changes,patterns in sodium dodecyl sulfate-polyacrylamide gel electrophoresis,and differential scanning calorimetry.These results indicated that MP was modified by additive reactions between the quinone of EGCG and thiols and free a mines of proteins.These adducts increased cooking loss and destabilized the texture,especially with a large EGCG dose.Confocal laser scanning microscopy and scanning electron microscopy images clearly indicated the damage to the emulsifying properties and the collapse of the internal structure when the MP emulsion gel was treated with a large EGCG dose.A high concentration of NaCl(0.6 M)improved modification of MP and increased the rate of deterioration of the internal structure,especially with the large EGCG dose(1000 ppm),resulting in an MP emulsion gel with extremely unstable emulsifying properties.