多酚抑制猪肉蛋白氧化体系中亚硝胺的形成机理

Both fresh and processed meats are susceptible to oxidative reactions due to the presence of prooxidants. The complex nitrosation process leading to the formation of nitrosamine can start with any of the following nitrogen compounds: nitrite, nitrate, primary, secondary, and tertiary amines, amides, proteins, peptides, and amino acids. The degradation of proteins into small molecule compounds could be a reason for the nitrosamine generation. Our previous studies have shown that the nitrosamine was effectively inhibited by high content polyphenols in Chinese dry-cured sausages. However, there was a little information about the mechanism of nitrosamine formation. This project was based on the oxidation of myofibrillar proteins and sarcoplasmic proteins. Protein oxidation was evaluated using multiple indexes, including carbonyl content, sulfhydryl content, SDS-PAGE electrophoresis and the free amines content. In a simulated thermal processing system, the relationship between the generation of nitrosamines and the degree of oxidation was evaluated. Then the effect of polyphenols on nitrosamine formation was determined, the relationship between the chemical structure of phenols and nitrosamines was analyzed. Finally, separate and identification the nitrosoquinone oxime derivative through LC-MS/MS and NMR. The results of this study will provide a scientific theoretical basis for the quality control of meat products and application of natural extracts.

肉类在加工和贮藏过程中，蛋白质和脂肪极易发生氧化，蛋白质氧化降解产物促进了亚硝化。我们前期研究发现，高浓度的多酚具有抑制传统中式香肠中亚硝胺生成的作用，但其作用机理尚不清楚。本项目拟采用氧化的肌原纤维蛋白和肌浆蛋白为材料，在模拟肉制品热加工体系中，通过测定羰基值、巯基含量、SDS－PAGE电泳和游离胺含量，研究蛋白质氧化程度与亚硝胺生成之间的关系；通过分析酚类物质的化学结构与亚硝胺生成之间的关系，研究茶多酚和酚类单体对亚硝胺生成的影响；最后通过LC-MS/MS和NMR光谱分析反应体系中可能的中间产物－亚硝基苯醌肟类衍生物，揭示酚类抑制亚硝胺形成的机理，为肉制品的品质控制及天然提取物的科学应用提供理论依据。

肉类在加工和贮藏过程中，蛋白质和脂肪极易发生氧化，蛋白质氧化降解产物促进了亚硝化过程。本项目在前期研究的基础上，通过蛋白氧化体系和模拟胃酸反应体系，研究肌原纤维蛋白的氧化程度与亚硝胺生成之间的关系，分析了肌原纤维蛋白的侧链结构变化与亚硝胺生成的相关性。随双氧水浓度的升高，猪肉肌原纤维蛋白游离巯基含量下降，表面疏水性增加，二聚酪氨酸含量升高，内源色氨酸荧光强度降低，说明蛋白质氧化程度增加。肌原纤维蛋白氧化程度越高，亚硝胺的生成量越多。通过研究抗氧化剂茶多酚、绿原酸、芦丁、槲皮素、EC、EGCG对蛋白氧化体系中肌原纤维蛋白的侧链结构以及亚硝胺生成的影响。发现氧化处理后，随着多酚质量浓度的增加，蛋白质游离巯基和内源色氨酸荧光强度逐渐增加，表面疏水性呈下降趋势。酚类化合物在低浓度时促进亚硝胺的生成，而高浓度则抑制了亚硝胺生成。结构分析发现，具有A环间位酚羟基结构的化合物具有促进和抑制亚硝胺生成的双重功效。本研究在肌原纤维蛋白氧化体系中，揭示了酚类物质抑制亚硝胺形成的机理，为肉制品的品质控制及天然提取物的科学应用提供理论依据。