摘要
以邻苯二酚为底物,采用分光光度法在420 nm处测定冬瓜多酚氧化酶(PPO)的活性,研究了不同温度和pH值对其活性的影响,并建立了酶促褐变反应动力学方程,探讨了抗坏血酸、亚硫酸氢钠、柠檬酸和EDTA-2Na 4种抑制剂对冬瓜酶促褐变的抑制效果。结果表明,冬瓜多酚氧化酶的最适温度为20℃,最适pH值为6.0;冬瓜多酚氧化酶的米氏方程符合单底物酶促反应动力学,相应的动力学参数为Km=0.0118 mol/L,Vm=0.0586 U/min;化学抑制剂抗坏血酸、亚硫酸氢钠、柠檬酸和EDTA-2Na对多酚氧化酶都有抑制作用,其活性分别为对照的25%、32%、62%和57%。
The activity of wax-gourd polyphenol oxidase（PPO） was spectrophotometer at 420 nm using catechol as substrate. The effects of temperature, pH and inhibitors on PPO were studied and the reaction kinetic equation was established. The results showed that the optimum temperature and pH were 20℃ and pH 6.0 respectively. The reaction kinetic equation of enzymatic browning in this experiment built accorded with Michaelis equation modle. The Km, Vmax of kinetic equation were 0.0118 mol/L, 0.0586 U/min using catechol as substrate, respectively. The four inhibitors as ascorbic acid, NaHSO3 critic acid and EDTA-2Na had different effects on inhibiting enzymatic browning. These activity of PPO decreased to 25%, 32%, 62% and 57%.
出处
《食品科技》
CAS
北大核心
2008年第2期11-14,共4页
Food Science and Technology
关键词
多酚氧化酶
冬瓜
褐变
抑制剂
polyphenol-oxidase
wax-gourd
browning
inhibitor
