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

In cured meat products, we often add sodium nitrite(Na NO2), because it can contribute to the product’s attractive color, unique flavor and can limit microbial growth and delay the development of oxidative rancidity. Addition, it also can improve the stability of products and prevent oxidation of myofibrillar protein. Hence, in this paper, we selected pork as material, and investigated the effects of different doses of Na NO2 on the physiochemical and structural characteristics of myofibrillar protein(MP) in ham, tried to reveal the relationship between nitrosation and oxidation of protein, explored the mechanism of nitrite in ham, and provided theoretical basis for the development of cured meat products and new methods of protein modification for the future. Results of this work showed that the addition of Na NO2 significantly affected all measured parameters of oxidative and nitrosative modification of MP. The heat treatment also significantly affected the carbonyl, free amine, and dityrosine content of MP. The main contents and results are indicated as follows:(1)First this study investigated the effects of different doses of Na NO2 on the oxidation of myofibrillar protein(MP) in ham, and mainly measured carbonyl, dityrosine, sulfhydryl, disulfide bond, from the data, the Na NO2 showed a dose-dependent antioxidant effect, by inhibiting carbonyl formation, dityrosine formation, and denaturation of MP.(2)Exploring the different levels of Na NO2 had effects on myofibrillar protein during heating, and then determined the carbonyl group, the content of free amino, thiol and disulfide bond, asa result heating treatment made protein denaturate and easily oxidative, with Na NO2 protein showed better antioxidant effect, the carbonyl of cooked ham below the raw ham, because protein structure changed and peptides cracked, with Na NO2, carbonyl and amino covalent binding, nitroso protein, during heating, nitrite promoted thiol formation disulfide bond, causing a significant rise in disulfide bond content, while sulphur content is lower. It proved out the its antioxidative, so did the SDS-PAGE.(3)With the action of Na NO2, protein could be nitrosylation, that protein and nitrite reaction generated 3-nitro tyrosine was found. The results were shown that 3-nitro tyrosine content had a close relationship with protein oxidation degree, its content in the raw ham had significantly positive correlations with the content of Na NO2, when adding 400 mg/kg Na NO2 in ham, 3-nitro tyrosine reached 23 nmol/mg, and the content of 3-nitro tyrosine and negatively correlated with sulfhydryl and surface hydrophobicity; in cooked ham, Na NO2 was 400 mg/kg 3-nitro tyrosine content was 15 nmol/mg, had negative correlations with carbonyl, sulfhydryl content and turbidity, turbidity, and disulfide bond content show significant positive correlation. It illustrated the 3-nitro tyrosine could serve as a kind of potential characterization of protein oxidation markers, and could be used in raw and cooked marinated meat products.