超高压处理对鲜榨苹果汁中多酚氧化酶活力的影响

Studies on Effect of Ultrahigh Pressure Treatment on PPO Activity in Fresh Apple Juice

使用超高压技术单独或协同热对鲜榨苹果汁进行处理,研究对其中多酚氧化酶(PPO)的影响。结果表明,200～500MPa的压力处理使果汁中PPO活力逐渐降低,但降低幅度不大,300MPa的压力对PPO的影响最小。高于600MPa的压力PPO开始失活。VC在500MPa以下对果汁中PPO有激活作用,在600MPa以上或热处理结合高压时有钝化PPO的作用。随着保压时间的延长和温度的升高,苹果汁中多酚氧化酶相对活性逐渐降低。400MPa、50℃以上的处理强度可使鲜榨苹果汁中的PPO失去60%以上的活力,750MPa、50℃以上的处理强度相应的PPO失活率可达90%以上,果汁颜色变化在考察的条件下不显著(△E为0.6)。

The ultrahigh pressure technology alone or combined with heating was used in processing fresh apple juice and the its effect on PPO activity in juice was studied. As the pressure increased,the activity of PPO in juice reduced slowly during the pressure scope of 200MPa-500MPa and the effect of pressure on activity was lest when the pressure was 300 MPa. Ef- fect of pressure on inactivation of PPO became remarkable when pressured above 600 MPa. PPO was activated by adding VC into juice when pressured below 500 MPa and was inactivated when pressured above 600 MPa or combined with heating. The activity of PPO in juice decreased as the increasing of heating temperature and pressure holding time. The treatment of 400MPa above 50℃ could inactivate PPO activity by 60% and 750 MPa above 50℃ could inactivate more than 90% activity,the color change of juice （△E） was 0.6.