A Study On The Characteristics Of Myofibrillar Protein From PSE Pork Before And After Oxidation

PSE pork, for its pale color, lack of firmness, and fluid dripping from its cut surfaces, is flawed in its surface, color, taste, water-retention and alike after processing, and thus is not favored by the production processor and the consumers. However, with the effect of the endogenous protease, the cytoskeletal protein of myofibrillar proteins from PSE pork(MPP)degrades and weakens the structure, and occupies higher protein hydrolysis. We speculate that the PSE pork possesses higher nutritional value than the ordinary pork in myofibrillar protein(MPN). Besides, the nutritional quality of MPP has barely been researched so far. On account of this, this thesis chooses the PSE pork and the ordinary pork as raw material, and explores the effect of hydrogen peroxide oxidation on the physicochemical property, organizational structure, and In Vitro Organic. In vitro digestion of the MPP and MPN. This thesis intends to help the production processors, researchers and the consumers to understand the nutritional value of the PSE pork. The main contents of this thesis are as follow:(1)Myofibrillar proteins are oxidized for 12 h at 4℃ by a hydroxyl radical generating system. In such condition, the MPP and MPN is handled, the carbonyl groups content, amino group content, dimer content of tyrosine, total sulphur content, disulfide bond content and the solubility variations are measured and then the analysis of the physicochemical property variation is conducted. The experimental result shows that after oxidation, MPP possesses remarkably higher carbonyl groups content, disulfide bond content, solubility, but lower dityrosine content. All of the above indicates the MPP is easier to be oxidized.(2)The effect of the oxidation of the organizational structure on MPP and MPN is analyzed. The surface hydrophobicity and the protein level are measured; Protein particle size analysis in conducted through the dynamic light scattering to grasp the protein aggregation intensity; SDS-PAGE polyacrylamide gel electrophoresis is conducted, and the protein aggregation condition with oxidation is observed. It can be obtained through the experiment that MPP is lower in the aggregation extent, and higher in the surface hydrophobicity and has loose structure. The bands of SDS-PAGE polyacrylamide gel electrophoresis also indicates the MPP possesses lower aggregation extent, and lower Carbonyl and amino interaction.(3)In vitro digestion of MPP and MPN with the effect of pepsin and trypsin and alpha chymotrypsin is explored, and the nutritional values are analyzed. As can be seen from the experiment results, pepsin and trypsin have the similar effect on in vitro digestibility of protein. With the effect of the oxidation on the endogenous protease, MPP hydrolyzes, and is oxidized into tiny fragments, reaches critical concentration gradually and increases the solubility, and thus improves in vitro protein digestibility and overall digestibility. Besides, if the oxidative stress is strong enough(under the condition of 10 mm hydrogen peroxide), in vitro digestibility of MPN increases accordingly.