| 摘要: |
| 【目的】研究菊苣根多酚氧化酶（PPO）酶学特性的影响因素，为菊苣根加工过程中酶促褐变的控制提供参考。【方法】以菊苣新鲜根为材料，从供试的3种三元酚、5种二元酚和4种单元酚底物中选出最佳反应底物，分析所选择底物的浓度、PPO提取液添加量、pH、温度及抑制剂对菊苣根PPO活性的影响，同时研究PPO的酶促动力学特征。【结果】菊苣根PPO的最适底物为焦性没食子酸，其最佳浓度为40 mmol/L，菊苣根PPO的最适粗酶液添加量为0.4 mL，最适pH和反应温度分别为7.0和35 ℃。PPO酶促反应动力学符合米氏方程，酶促反应的动力学米氏常数为0.39 mmol/L，最大反应速率为217.39 U/min。控制pH在4.8以下，采用0.4 mmol/L柠檬酸和0.8 mmol/L L 抗坏血酸复配，90 ℃处理10 min或者100 ℃处理6 min，均可基本抑制菊苣根PPO的活性。【结论】通过选择合适的pH和温度，同时结合化学抑制剂调控菊苣根PPO活性，可以减少菊苣根加工过程中的酶促褐变，从而提高加工产品的品质。 |
| 关键词: 菊苣根 多酚氧化酶 酶学特性 |
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| 基金项目:吉林省科技发展计划青年科研基金项目（20100144）；国家级大学生创新创业训练计划项目（201210193011）；吉林农业大学大学生科技创新基金项目（2012ZR0504） |
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| Characterization of polyphenol oxidase in chicory root |
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| Abstract: |
| 【Objective】The aim of this research was to study the factors influencing the polyphenol oxidase (PPO) characteristics of chicory root,so as to improve the browning control in chicory root processing.【Method】Using fresh chicory roots as experimental materials,the optimum substrate was selected from 3 trihydroxyphenols,5 diphenols,and 4 monophenols,and the effects of the optimum substrate concentration,PPO extracting solution amount,pH value,temperature,and inhibitors on PPO activity,and the kinetics of the enzyme-catalyzed reaction of PPO were determined.【Result】The optimum substrate of PPO was pyrogallic acid,and the optimum concentration was 40 mmol/L.The optimal PPO extracting solution was 0.4 mL.The optimum pH value and reaction temperature were 7.0 and 35 ℃,respectively.Michaelis-Menten equation was obtained to express the kinetics of enzyme-catalyzed reaction of PPO with Michaelis constant and maximum reaction rate values of 0.39 mmol/L and 217.39 U/min,respectively.The enzyme activity was greatly inhibited when pH value was below 4.8,combination of 0.4 mmol/L citric acid and 0.8 mmol/L L-ascorbic acid,temperature at 90 ℃ for 10 min,or 100 ℃ for 6 min.【Conclusion】Browning phenomenon in chicory root processing can be controlled and the quality of products can be improved by selecting appropriate pH,temperature,and combining with chemical inhibitors. |
| Key words: chicory root polyphenol oxidase enzymology characteristics |
