摘要
茄子多酚氧化酶(polyphenol oxidase,PPO)是引起酶促褐变,导致果实褐变的主要原因。采用匀浆法从茄子中提取多酚氧化酶粗液,以邻苯二酚为底物,在λ420nm处研究温度、pH值、底物浓度对茄子果实中PPO活性的影响,建立相应的酶促褐变反应动力学方程。探讨L-半胱氨酸、抗坏血酸、亚硫酸氢钠、柠檬酸4种抑制剂对茄子酶促褐变的抑制效果。结果表明,茄子多酚氧化酶的最适温度为30℃,最适pH值为6.0及8.5(可能存在同工酶),酶促褐变反应动力学符合米氏方程所描述的单底物酶促反应动力学,相应的动力学参数Km=0.0215U(/min·g),Vmax=0.539U/(min·g),相应的动力学方程为V=0.539[S]/(0.0215+[S]);供试4种抑制剂防止果实褐变的效果由强到弱依次是:抗坏血酸、亚硫酸氢钠、L-半胱氨酸、柠檬酸。另外,茄子PPO对高温较为敏感,在100℃时加热105s可钝化酶活性。
The properties of polyphenol oxidase extracted from eggplant were investigated. The eggplant polyphenol oxidase activities were spectrophotometrically determined at 420 nm with catechol as substrate in different temperature, pH and substrate concentration. The reaction kinetic equation was also established in this study. The results showed that the optimum temperature and pH of eggplant polyphonel oxidase＇ s was 30 ℃ and pH 6.0 and 8.5（ likely to have the isoenzyme）, respectively. The reaction kinetic of enzymatic browning is accordant with Michaelis equation, the Km and Vmax were 0.0215 U/（min .g） and 0.0539 U/（min .g）, respectively. The equation of kinetics were V=0.539 [S]/0.021 5＋[S]）.The orders of inhibition effect from strong to weak were from Vc, NaHSO3, L-Cys to Citeic Acid in this research.
出处
《食品研究与开发》
CAS
北大核心
2009年第6期48-52,共5页
Food Research and Development
关键词
茄子
多酚氧化酶
酶促褐变
抑制剂
eggplant
Polyphenol Oxidase （PPO）
browning
inhibitor
