在pH 0.5~12.5的范围内，采用碱溶法制备了罗非鱼鱼糜（TS）。研究表明，随着pH值的升高，TS蛋白回收率得到显著提高，但在pH值由11.5升至12.5时，得率仅提高11.56%，而碱液耗费却增加了77.65%；pH值的升高使溶解蛋白的ATP酶活性急剧降低（51.80%→0%），而表观疏水性则表现出增强趋势，表明pH值的升高促进了肌球蛋白的构象展开。电泳结果显示，pH值升高并未使等电点处可溶性蛋白及TS中蛋白组分发生明显变化。pH值的升高使TS白度先升高（75.40→80.50），之后下降（→76.20）；TS凝胶破断力也表现出先升高后下降的趋势（290.00→335.20→278.80 g），表明极端的碱性条件（>pH12.0）会对TS凝胶品质产生负面影响。TS凝胶的电泳结果表明，不同pH值条件下提取的TS所制备的凝胶蛋白组分之间没有明显差别，并且TS凝胶形成过程中没有显著的肌球蛋白交链发生，意味着TS中内源谷氨酰胺转胺酶（TG酶）活性相对于传统鱼糜变得很低，这可能是由于在等电点处离心时TG酶与TS发生了分离。

Tilapia surimi (TS) was prepared by alkaline solubilization/isoelectric precipitation (pH-shift) in the pH range 10.5~12.5. On increasing the pH values, the protein recovery from TS significantly increased. However, when the pH value was increased from 11.5 to 12.5, the protein recovery only increased by 11.56%, while the alkali consumption increased by 77.65%. The increased pH values sharply decreased the ATPase activity of solubilized proteins (51.80→0%), but increased the surface hydrophobicity, indicating that increasing the pH values promoted the unfolding of myosin. The electrophoresis results showed that increasing the pH values did not cause significant differences in the composition of soluble protein at the isoelectric point (pI). As the pH value increased, the whiteness of TS first increased from 75.40 to 80.50, and then decreased to 76.20; the breaking force of the TS gel also decreased after an initial increase (290.00 → 335.20 → 278.80 g). Both the aforementioned results suggested that treatment under extreme alkaline conditions (pH >12.0) produced a negative effect on the quality of the TS gel. The electrophoresis results of the TS gel suggested that no significant differences were found in the protein compositions of gel proteins prepared at different pH values. In addition, no significant cross-linking occurred in myosin during the formation of the TS gel, indicating that the activity of endogenous transglutaminase (TGase) was very low compared to that in traditional surimi. This was probably due to the separation between TGase and TS at the pI during the second centrifugation.

中央农业科技专项（粤财农[2012]480号）；广东省海洋渔业科技专项（A201301C07）