超高压处理对梨汁中多酚氧化酶活性的影响

http://www.100md.com 2007年1月1日 赵光远 李 娜 纵 伟

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     摘要：目的研究鲜榨梨汁中多酚氧化酶(PPO)的活性受高压和热协同处理的影响。方法使用超高压技术单独或协同加热处理加或不加维生素C的鲜榨梨汁，测定其中PPO活性和果汁颜色。结果200~600 MPa的压力处理对果汁中PPO活性影响不大，400 MPa的压力对PPO有激活作用；高于600 MPa的压力使PPO显著失活。维生素C在500 MPa 以下对果汁中PPO有激活作用，在600 MPa 以上或热处理结合高压时有钝化PPO的作用。随着保压时间延长和温度升高，梨汁中PPO相对活性逐渐降低。500 MPa 60 ℃或750 MPa 50 ℃以上的处理条件可使鲜榨梨汁中的PPO失去60%以上的活性，750 MPa 50 ℃的处理条件下果汁颜色变化不显著。结论梨的PPO是耐高压的酶。

    关键词：鲜榨犁汁；多酚氧化酶；超高压；酶促褐变；颜色

    中图分类号：Q0521+.9文献标识码：A文章编号：1672-979X(2007)01-0015-04

    Study on Effect of High Pressure Treatment of Fresh Pear Juice on PPO Activity

    ZHAO Guang-yuan1, LI Na2, ZONG Wei1

    (1. School of Food and Bioengineering, Zheng Zhou Light Industry College, Zhengzhou 450002, China；

    2.School of Luo He Food Industry, Luohe 462000, China)

    Abstract：Objective To study the effect of high pressure alone or combined with heating treatment of fresh pear juice on PPO activity in it. Methods The ultrahigh pressure technology alone or combined with heating was used in the processing of fresh pear juice added VC or not, and then the color of juice and activity of PPO in it was assayed. Results As the pressure used increased, the activity of PPO in juice did not change significantly during the pressure scope of 200MPa~600MPa and 400 MPa could activate PPO in juice. Effect of pressure on inactivation of PPO became remarkable when pressured above 600 MPa. PPO in juice added VC was activated when pressured below 500 MPa and was inactivated when pressured above 600 MPa or combined with heating. The activity of PPO in juice decreased step by step with the increasing of heating temperature and pressure holding time. The treatment of 500 MPa above 60 ℃ or 750 MPa above 50 ℃ could inactivate PPO by 60% activity and the color change of juice was insignificant under the condition of 750 MPa above 50 ℃(△E was 0.9). Conclusion PPO in pear juice is hardly inactivated by high pressure.

    Key words：fresh pear juice; PPO; ultrahigh pressure; enzymatic browning; color

    水果中的多酚氧化酶(PPO)催化酚类物质在有氧气的条件下生成褐色物质称为酶促褐变，鲜榨梨汁生产的一大难题是防止酶促褐变。可借鉴苹果加工中采用的防止褐变的相关方法，如使用防褐变剂[1]，水果破碎时充氮气[2]，高压使酶失活[3]，电渗析法调果汁pH值[4]，水果破碎时热蒸汽处理[5]及使用脉冲电场[6]等。在这些方法中，热处理虽能很好地杀灭果汁中的微生物和酶，从而延长果汁的货架期，但对果汁的品质影响较大，而高压和使用脉冲电场是最有潜力的技术 ......

    http://www.100md.com/html/paper/1672-979X/2007/01/05.htm

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