牛蒡多酚氧化酶的特性及酶促褐变的抑制

Characterization of polyphenoloxidase and inhibition of enzymatic browning in burdock

采用制作丙酮粉的方法提取了牛蒡中的多酚氧化酶(PPO),并对其酶学特性进行了研究。实验结果表明,牛蒡多酚氧化酶最适温度为40℃,最适pH为6.0,在40℃下热稳定性较好,而在70℃加热3min即可使其完全失活。牛蒡PPO的米氏常数为0.1337mol/L,最大反应速率Vmax为7.387U/min。通过响应面实验设计的方法对防止牛蒡酶促褐变的配方进行了优化,结果表明当复合护色液中EDTA、L-半胱氨酸和柠檬酸亚锡二钠的护色剂的浓度都为0.04%(w/v)时,牛蒡的褐变度最小。

An acetone powder was prepared from burdock for extracting polyphenoloxidase（PPO）,and the characterization of PPO was studied.The results indicated that burdock PPO had a optimum pH of 6.0,showing maximum activity at 40℃.Heated for 3min,PPO of burdock would been inactivated completely,though it showed very stable at 40℃.The Km of burdock PPO was 0.1337mol/L,while its Vmax was 7.387U/min.Response surface methodology was adopted to optimize the combination of antibrowning agents.When the concentration of EDTA,L-cystine and distannous citrate in antibrowning solution was 0.04%,the browning degree of burdock was the lest.