低温等离子体处理加速罗非鱼肌原纤维蛋白的氧化及结构改变

以新鲜罗非鱼为研究对象，采用不同时间（0、1、2、3、4、5 min）和电压（40、50、60、70、80 kV)进行处理，分析处理后鱼肉的羰基含量、巯基含量、疏水性、Zeta电位、SDS-PAGE凝胶电泳、紫外光谱、荧光光谱和拉曼光谱，探究低温等离子体处理对罗非鱼肌原纤维蛋白氧化及结构的影响。结果表明:随着低温等离子体处理时间延长及电压升高，鱼肉中羰基含量和疏水性逐渐增加，总巯基和活性巯基含量减少；当处理时间延长至5 min时，总巯基和活性巯基分别减少至66.91 和52.76 μmol/g；处理电压升高至80 kV时，羰基含量从1.23 nmol/mg上升至2.16 nmol/mg；处理低温等离子体处理使肌原纤维蛋白Zeta电位绝对值降低；SDS-PAGE表明，低温等离子体处理使肌原纤维蛋白的肌球蛋白重链条带加重；随着低温等离子体处理时间的延长及电压的升高，紫外吸收光谱蓝移并且吸收强度增强，荧光吸收强度减弱；鱼肉经高电压、长时间等离子体处理后，α-螺旋增加，β-转角和β-折叠减少，无规卷曲无明显变化。综上，低温等离子体处理能够加速肌原纤维蛋白氧化，导致蛋白质的二级结构和构象发生改变。

Cold Plasma Treatment Accelerated the Oxidation and Structural Changes of Myofibrillar in Tilapia

To investigate the effects of cold plasma treatment on the oxidation and structure changes of myofibrillar proteins tilapia, the fish was treated by cold plasma with different time (0, 1, 2, 3, 4, 5 min) and different voltage (40, 50, 60, 70, 80 kV), respectively, the carbonyl content, sulfhydryl content, hydrophobicity, Zeta potential, SDS-PAGE, UV spectra, fluorescence spectra and Raman spectrometer of myofibrillar protein were measured after treatment. The results showed that the carbonyl content and surface hydrophobicity of myofibrillar protein were increased gradually, as the treatment time extending or voltage increased, while the total sulfhydryl and the active sulfhydryl content were decreased. When the treatment time was extending to 5 min, the total sulfhydryl and the active sulfhydryl content were decreased to 66.91 and 52.76 μmol/g, respectively. The carbonyl content increased from 1.23 to 2.16 nmol/mg, if the treatment voltage was increased to 80 kV. Cold plasma treatment decreased the absolute value of Zeta potential of myofibrillar protein. The myosin heavy chain band of myofibrillar protein was increased based on SDS-PAGE results. As treatment time extending and voltage increasing, the UV spectrum of myofibrillar protein was blue-shifted with an increased UV absorption intensity, and the fluorescence absorption intensity of protein was weakened. Based on the Raman spectrometer determination, the content of α-helix was increased, the contents of β-sheet and β-turn were reduced, and the random coils had no obvious changes in myofibrillar protein of tilapia after cold plasma treatment. In conclusion, extending the treatment time or increasing treatment voltage of cold plasma can accelerate the oxidation of myofibrillar protein to result in the changes of their second-order structure and conformation.