压力水平及氯化钠浓度对兔肌球蛋白凝胶保水性及其胶凝过程中理化特性和结构变化的影响

以含不同浓度的氯化钠(1.0%、1.5%、2.0%)的兔骨骼肌肌球蛋白为实验对象,在不同压力水平(100、200、300 MPa)下对其进行超高压处理(9 min,25 ℃)后加热制备凝胶。以未经高压处理的含2%氯化钠的蛋白作为对照组。根据凝胶保水性、水分分布、凝胶微观结构、蛋白在升温过程中的贮能模量、表面疏水性、活性巯基含量以及二级结构等指标的变化,研究压力水平及氯化钠浓度对经高压处理的肌球蛋白加热胶凝过程中的蛋白流变特性,二三级结构以及形成的热凝胶的水分特征的影响。结果显示:含1%氯化钠的兔肉肌球蛋白经100或200 MPa高压处理后,包埋的疏水基团和巯基在40~55 ℃间快速暴露,且蛋白中的α-螺旋结构的比例也显著下降(p<0.05)。其较高的热变性速率使蛋白分子得以充分解折叠与相互作用,最终形成的热凝胶的保水性,微观结构及贮能模量均优于其他处理组,该研究结果可为利用超高压技术生产低盐功能性肉制品提供理论依据。

Effects of pressure level and sodium chloride contents on the water-holding capacity of rabbit myosin gel and its physiochemical properties and structural changes during gelling

By using myosin extracted from rabbit skeletal muscles as experimental material, which contained different amounts of sodium chloride (1.0%, 1.5%, 2.0%)and subjected to various levels (100, 200, 300 MPa)of high pressure treatment (9 min, 25℃)before heating. The effects of pressure levels and sodium chloride contents on the rheological properties and conformational structures of protein during gelling as well as the water characteristics of formed gel were investigated. The water holding capacity, water distribution and the microstructure of gel as well as the storage modulus, surface hydrophobicity, reactive sulfhydryl contents and the secondary structures of protein during heating were measured. Unpressurized myosin with 2% sodium chloride content was set as control. The results showed that rapid exposure of hydrophobic and sulfhydryl groups happened in 100 and 200 MPa treated myosin with 1% sodium chloride content between 40 and 55℃ and the proportion of α-helix structures decreased simultaneously (p<0.05). All these phenomenon indicated that its higher rate of denaturation allowed sufficient unfolding of myosin during heating, which resulted in higher water holding capacity and final storage modulus as well as better microstructure of gel than others. It can provide valuable reference for the broader application of high-pressure technology to industry.