罗非鱼肉盐溶性蛋白的分离及其物化性质分析

Isolation and Properties of Salt-soluble Protein from Tilapia Muscle

本研究以罗非鱼为原料,采用化学方法分离盐溶性蛋白,并对其热稳定性和酸碱稳定性进行检测和分析。热稳定性研究显示,随着热处理时间的延长和温度的升高,蛋白质热变性和聚集的速率明显增大。在试验范围内,40℃条件下处理时,在热处理30 min内,体系浊度变化不明显;而随着温度的升高,盐浓度对盐溶性蛋白热变性的影响比较明显;50℃时0.3 mol/L KCl盐溶性蛋白的聚集速率为0.6 mol/L KCl盐溶性蛋白速率的6.8倍。酸碱稳定性分析显示,酸性调节（pH 3.0-7.0和4.0-7.0）处理使盐溶性蛋白的溶解性下降,活性巯基含量减少,体系的乳化性能减弱,且低盐浓度提取蛋白的酸碱稳定性更差;而碱性调节（pH 9.0-7.0和11.0-7.0）处理可使盐溶性蛋白的溶解性升高,活性巯基变化不明显,因此,盐溶性蛋白的碱稳定性较好。但酸/碱调节处理均使盐溶性蛋白的Ca2＋-ATPase活性明显降低,蛋白质分子相对表面疏水性升高。另外,脱盐会导致盐溶性蛋白的Ca2＋-ATPase活性丧失,蛋白的稳定性明显变差。

Salt soluble protein was separated using chemical method from Tilapia meat in this study,and thermal stability and pH stability were determined.Study of the thermal stability of salt soluble protein showed that,the rates of protein thermal denaturation and aggregation were significantly increased with the increase of heating time and heating temperature.Within the temperature of 40 ℃,heating treatment for 30 min showed little effect on the turbidity of protein system.When the temperature increased,the salt concentration showed significant effect on the denaturation rate of salt soluble protein.The aggregation rate of the salt-soluble protein in 0.3 mol/L KCl was 6.8 times higher than that in 0.6 mol/L KCl at 50 ℃.The pH stability of salt soluble protein analysis showed that the pH-shifting treatment from pH 3.0 to 7.0 and from 4.0 to 7.0 reduced the solubility of salt soluble protein,the content of active thiol,the emulsifying properties and the stability of salt soluble protein extracted by low concentration of salt.The pH-shifting treatment from pH 9.0 to 7.0 and from 11.0 to 7.0 increased the solubility of salt soluble protein,while the content of activity sulfhydryl did not change significantly.Therefore,the stability of salt soluble protein was higher at alkali condition.However,both the acid and alkali adjustment reduced the Ca2＋-ATPase activity of salt soluble protein significantly and increased the relative surface hydrophobicity of protein molecules.Besides,the desalination of salt soluble proteins resulted in loss of Ca2＋-ATPase activity,and the stability of the protein was significantly worse.