超高压处理对多酚氧化酶活性的影响

 研究了超高压中温协同处理对砀山梨汁中多酚氧化酶活性的影响，实验压力为0.1~500 MPa，温度为20~60 ℃。此外，考察了不同pH值（3~7）和保压时间（2~34 min）超高压处理对酶活性的影响。实验结果分析表明：在处理温度为50 ℃、保压时间为10 min和梨汁pH值为5的条件下，200~300 MPa处理梨汁时多酚氧化酶被激活，活性表现最高；500 MPa时酶的活性下降到75.3%。协同温度为30 ℃处理梨汁时，酶的活性反而增大；30 ℃以后，酶活性随温度升高而迅速降低；有效协同高压处理的温度为40 ℃。随着保压时间的延长，梨汁中过氧化物酶的活性减小；18 min以前下降速度较快些，之后下降速度变缓。pH在5~6之间，酶的残留活性最大；pH值为6时，梨汁中多酚氧化酶最为耐压。

Effect of High Pressure (HP) Treatments on Polyphenoloxidase (PPO) Activity in Pear Juices

The effect of high hydrostatic pressure treatment (0.1~500 MPa) combined with mild heat treatment (20~60 ℃) under different pH values (3.0~7.0) on polyphenoloxidase (PPO) activity of Chinese Dangshan pear juice was investigated in this paper. Results showed that the polyphenoloxidase was activated when the high pressure treatment on the pear juice was carried out under the temperature 50 ℃, the dwell time 10 min, the pH5 and the pressure between 200~300 MPa. The polyphenoloxidase activity reached the maximal level under temperature of 30 ℃ synergizing high pressure treatment, and decreased under the temperature of above 30 ℃. The polyphenoloxidase residual activity was rapidly decreased with the increasing of dwell time. The polyphenoloxidase residual activity and the pressure resistance reached their maximal level under pH6.