Jiangxi Key Laboratory of Natural Products and Functional Food, Jiangxi Agricultural University, Nanchang 330045, China.
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Poult Sci. 2017 Sep 1;96(11):4116-4123. doi: 10.3382/ps/pex213.
This study investigated the effects of copper ions on egg white (EW) gel induced by strong alkali. Changes in gel characteristics were examined through texture profile analysis, scanning electron microscopy (SEM), and chemical methods. The value of gel strength reached its maximum when 0.1% copper ions was added. However, the lowest cohesiveness values were observed at 0.1%. The springiness of gel without copper ions was significantly greater than the gel with copper ions added. SEM results illustrated that the low concentration of copper ions contributes to a dense and uniform gel network, and an open matrix was formed at 0.4%. The free and total sulphhydryl group content in the egg white protein gel significantly decreased with the increased copper. The increase of copper ions left the contents of ionic and hydrogen bonds basically unchanged, hydrophobic interaction presented an increasing trend, and the disulfide bond exhibited a completely opposite change. The change of surface hydrophobicity proved that the main binding force of copper induced gel was hydrophobic interaction. However, copper ions had no effect on the protein component of the gels. Generally, a low level of copper ions facilitates protein-protein association, which is involved in the characteristics of gels. Instead, high ionic strength had a negative effect on gels induced by strong alkali.
本研究考察了铜离子对强碱诱导的蛋清（EW）凝胶的影响。通过质构分析、扫描电子显微镜（SEM）和化学方法研究了凝胶特性的变化。当添加 0.1%的铜离子时，凝胶强度达到最大值。然而，在 0.1%时，凝胶的内聚性值最低。不含铜离子的凝胶的弹性明显大于添加铜离子的凝胶。SEM 结果表明，低浓度的铜离子有助于形成致密均匀的凝胶网络，而在 0.4%时形成开放的基质。蛋清蛋白凝胶中的游离巯基和总巯基含量随铜的增加而显著减少。铜离子的增加使离子键和氢键的含量基本保持不变，疏水力呈现出增加的趋势，二硫键则表现出完全相反的变化。表面疏水性的变化证明了铜诱导凝胶的主要结合力是疏水力。然而，铜离子对凝胶的蛋白质成分没有影响。一般来说，低水平的铜离子有利于蛋白质-蛋白质的结合，这与凝胶的特性有关。相反，高离子强度对强碱诱导的凝胶有负面影响。
