烹饪熟度对牛肉肌原纤维蛋白结构特性和氧化特性的影响

为了研究烹饪过程肌原纤维蛋白结构的变化规律,本研究以不同熟度(未加热处理(对照组)、一分熟、三分熟、五分熟、七分熟、全熟和过熟)的牛背最长肌肌原纤维蛋白为研究对象,分析比较在熟制过程中,烹饪熟度对蛋白聚集特性、氧化程度的影响,并检测蛋白二级结构相对含量的变化.结果表明,烹饪过程明显影响肌原纤维蛋白的聚集行为、氧化特性和...

Effect of Degree of Doneness on Structural and Oxidation Properties of Beef Myofibrillar Protein

This study aimed to compare the differences in myofibrillar protein aggregation, oxidation and structural properties among beef M. longissimus dorsi cooked to different degrees of doneness (control, rare, medium rare, medium, medium well, well done, and over cooked). The results showed that the cooking process significantly affected myofibrillar protein aggregation, oxidation and structural properties. As the degree of doneness increased, myofibrillar protein solutions gradually changed from an aggregated state to a cleaved one; the content of protein carbonyl increased gradually, and the surface hydrophobicity and sulfhydryl content increased first and then decreased; the fluorescence intensity of dityrosine and intrinsic fluorescence intensity increased first, then decreased and finally increased again. The results of attenuated total reflection Fourier transform infrared spectroscopy analysis showed that the degree of medium cooking was the turning point in the evolution of protein secondary structure. As the degree of doneness increased from control to medium, the β-sheet relative content decreased, while the α-helix relative content remained stable, the aggregation of protein was mainly through intramolecular interactions; as the degree of doneness further increased to over cooked, the β-sheet relative content increased gradually, the α-helix relative content increased first and then decreased, and the protein was mainly intermolecularly aggregated. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) studies indicated that myosin heavy chain, α-actin and actin were involved in the thermal aggregation of myofibrillar proteins. As the degree of doneness increased, the gray values of myosin heavy chain and actin increased first and then decreased, and the gray value of α-actin increased continuously. The exact mechanisms need further study. The results from this study can provide a theoretical basis for the optimization of the frying process and the quality control of steak.