高压脉冲电场对苹果多酚氧化酶的钝化效果

Effect of Pulsed Electric Field on the Activity of Apple Polyphenol Oxidase

摘要:

多酚氧化酶 （PPO） 促褐变影响苹果鲜果和果汁的品质。探讨高压脉冲电场 （PEF） 钝化苹果鲜果PPO的可行性。在电压、停留时间、频率、脉冲宽度等单因素试验的基础上，采用响应曲面分析法优化钝酶工艺。结果表明，PEF对红富士多酚氧化酶活性抑制的最佳条件为：电压25 kV，频率530 Hz，停留时间45 s和脉冲宽度8 μs，此条件下多酚氧化酶的抑制率达51.86%。鲜榨果汁的色值和褐变指数与PPO的相对活力直接相关。PEF处理能够抑制果汁的酶促褐变，与对照组相比，由最优钝化条件下处理的果块制备的果汁 （4 h时） 的色值极显著大于对照组 （P＜0.01），总可溶性固形物，pH值没有发生显著改变 （P＞0.05），还原型维生素C呈下降趋势，但下降不显著 （P＞0.05）。

Abstract:

The product quality of fresh apple and apple juice could be deteriorated by the enzymatic browning of polyphenol oxidase （PPO）. The possibility to deactivate of PPO through the pulsed electric field （PEF） was discussed. The condition to deactivate PPO enzymatic activity was optimized by the response surface analysis based on the results of single-factor experiments，such as voltage，residence time，frequency，and pulse width. The optimal condition was achieved with 25 kV of voltage，530 Hz of frequency，8 μs of pulse width，and 45 s of residence time，under which the inhibition rate of PPO activity reached to 51.86%. The color value and browning index of fresh prepared apple juice were directly related to the relative activity of PPO. PEF could inhibit the enzymatic browning of apple juice. For the apple juice prepared from the fruit treated under the optimal deactivation condition，the color value was significantly larger than that of the control group （P<0.01）. The content of total soluble solids and solution pH did not show significant change （P> 0.05），while the content of ascorbic acid decreased insignificantly （P>0.05）.