高强度超声作用下鲢鱼肌球蛋白的结构及流变学特性变化

以鲢鱼为原料提取纯化肌球蛋白，研究不同高强度超声处理条件（100、150、200、250 W分别超声3、6、9、12 min）下肌球蛋白链构象、二级结构及流变学特性的变化。结果表明：超声处理会降低肌球蛋白的低温自组装程度，使样品的零剪切黏度逐渐降低、流动性增大，并诱导肌球蛋白α-螺旋向较为松散的β-折叠和无规卷曲结构转变，促使包埋在分子内部的活性基团暴露出来。该结构变化有利于升温过程中分子间的交联，并降低凝胶化温度，适当的超声条件（100、150 W处理12 min）可提高肌球蛋白的凝胶形成能力，而超声功率过大（200、250 W处理12 min）则会降低其凝胶形成能力，选择适当的超声条件对鱼糜凝胶加工十分重要。

Effect of High Intensity Ultrasound on Structural and Rheological Properties of Myosin from Silver Carp

Myosin from silver carp was sonicated with varying powers (100, 150, 200 and 250 W) for 3, 6, 9 or 12 min. The changes in the chain conformation, secondary structure and rheological properties of myosin were evaluated by UV absorption spectroscopy, circular dichroism spectroscopy and a rheometer. It showed that the low-temperature self-assembly of myosin was depressed by high intensity ultrasound (HIU) treatment, resulting in decreased zero shear viscosity and increased fluidity. HIU treatment induced the conversion of myosin α-helix to relatively loose β-sheet and random coil, resulting in the exposure of active groups buried inside the molecules. This structural change was beneficial for forming intermolecular interactions during heating and reducing the gelation temperature. Furthermore, ultrasonic treatment under appropriate conditions (100 or 150 W for 12 min) could improve the gel-forming capacity of myosin, but it could lead to a decrease in the gel-forming capacity at too high powers (200 or 250 W for 12 min). Selecting the appropriate ultrasonic treatment is of great importance for improving gelation properties of surimi.