酸/碱溶解-等电点沉淀法回收罗非鱼蛋白的工艺优化及蛋白组成分析

摘要

Protein isolates was prepared from tilapia(Oreochromis niloticus)muscle by acid/alkaline solubilization-isoelec⁃tric precipitation processing in this study. Effect of pH value, ratio of raw material to extracting media and extracting time on soluble protein yield were examined in the extraction process. And then effect of pH value on precipitated protein yield from acid-soluble and alkali-soluble protein and subunit composition was determined as well. Results showed that the optimum dissolution conditions of protein recovery from tilapia muscle were pH 2.0, 3.0, 11.0, and 12.0, ratio of raw material to ex⁃tracting media of 1∶9(ω/v), and extraction time of 10 min. The soluble proteins strips included the typical fish protein elec⁃trophoresis pattern. The optimum precipitation condition of acid-soluble and alkali-soluble protein was pH 5.5. In the above four conditions, the recovered protein yields from Tilapia muscle were 61.59%-64.95%by acid/alkaline solubilization and precipitation processing. Compared with tilapia muscle protein, the higher salt-soluble protein proportion and lower wa⁃ter-soluble protein proportion(p<0.05)in four protein isolates were obtained. Comparatively, the protein isolates prepared by alkaline solubilization-isoelectric precipitation has less denaturation and more complete composition, and the water-solu⁃ble and salt-soluble protein proportion were higher than those of protein isolates by acid solubilization-isoelectric precipita⁃tion. However, partial degradation of myosin and loss of sarcoplasmic protein were observed during acid solubilization-iso⁃electric precipitation treatment. Therefore, alkali solubilization-isoelectric precipitation process was more suitable for recov⁃ery of fish protein isolates.%以罗非鱼（Oreochromis niloticus）肉为原料，采用酸/碱溶解-等电点沉淀法回收罗非鱼肌肉蛋白，主要探讨溶解pH值、料液比和溶解时间对可溶性蛋白得率以及沉淀pH值对可溶性蛋白沉淀得率及蛋白亚基组成的影响.结果表明，酸/碱溶解回收罗非鱼肉可溶性蛋白的最佳pH值为pH 2.0、3.0、11.0和12.0，料液比1∶9（ω/v），溶解时间10 min，可溶性蛋白种类齐全，包含了典型的鱼蛋白电泳条带；酸/碱可溶性蛋白的最佳沉淀条件为pH 5.5，在此条件下，溶解-沉淀过程的蛋白得率分别为61.59%-64.95%.与鱼肉蛋白相比，四种分离蛋白中盐溶性蛋白的比例均升高，水溶性蛋白的比例均降低（p<0.05）.比较而言，碱溶-等电点沉淀过程中鱼蛋白的变性程度较小，其水溶性组分和盐溶性组分所占的比例均较高，组成相对比较齐全，而酸提蛋白中肌球蛋白重链部分降解，少量肌浆蛋白损失.因此，碱溶-等电点沉淀法更有利于回收鱼肉分离蛋白.