利用了在硫基乙醇作用下，邻苯二甲醛（OPA）试剂与伯胺可以发生荧光反应，使用荧光分光光度计快速检测溶液中游离伯胺含量。应用此方法研究了加酶量、反应温度、反应时间、及反应pH对谷氨酰胺转氨酶(TGase)作用于大豆分离蛋白后对其游离伯胺含量的影响，并对主要影响因素利用响应面发进行优化，找出TGase反应条件的最佳组合。实验结果表明：加酶量20 U/g，反应温度为52 ℃，反应时间60 min，反应pH 7为TGase最佳反应条件，改性后每克大豆分离蛋白伯胺含量由0.059 μmol减少为0.028 μmol。

The content of free primary amine in the solution was determined by spectrophotometric assay according to that ο-phthaladehyde (OPA) reagent and primary amine could occur fluorescence reaction. The effect of dosage, reaction temperature, time and pH of transglutaminase (TGase) treatment on the free primary amine of soy protein isolate (SPI) was investigated with this method, and the influencial factors were optimized by response surface method. The results showed that the optimal reaction condition was TGase dosage 20 U/g, temperature 52 ℃, time 60 min and pH 7. After TGase-catalyzed modification, the free amine content of SPI were reduced from 0.059 μmol to 0.028 μmol.