摘要
以广西平乐大果山楂为原料,邻苯二酚为底物,采用分光光度法测定大果山楂多酚氧化酶(PPO)活性,考察p H、温度、热处理、底物浓度及抑制剂对PPO活性的影响,为控制其生产过程中酶促褐变提供参考。结果表明,以邻苯二酚为底物时,PPO酶促反应产物的最大吸收波长为420 nm,反应时间为3 min,最适p H为6.8,最适温度为45℃;90℃处理4 min,PPO基本失活,80℃处理6 min后,相对酶活性为19.75%;最适底物浓度为0.08 mol/L,PPO酶促动力学符合米氏方程,相应的参数Km=51.24 mmol/L,Vmax=54.53 U/min;在试验浓度条件下,5种抑制剂对大果山楂PPO活性均有抑制作用,氯化钠的抑制作用最弱,高浓度下,柠檬酸的抑制效果较EDTA、抗坏血酸、草酸要好。
In order to provide a reference for controlling the enzymatic browning of Malus domeri（Bois） Chev. in the production process, with Malus domeri（Bois） Chev. as raw material, using catechol as substrate, the enzymatic activity of polyphenol oxidase（PPO） from Malus domeri（Bois） Chev. was determined by spectrophotometry. The effects of p H, temperature, thermal stability, substrate concentration and inhibitor on the activity of PPO were investigated.The results showed that the maximum absorption wavelength of PPO enzymatic reaction product was 420 nm, the reaction time was 3 min, the optimum p H was 6.8, the optimum temperature was 45 ℃. The polyphenol oxidase was inactivated after treated at 90 ℃ for 4 min, and the relative enzyme activity was 19.75% when treated at 80 ℃ for6 min. The optimal substrate concentration of PPO was 0.08 mol/L and the PPO enzyme followed Michaelis-Menten kinetics. The Kmand Vmaxvalues were 51.24 mmol/L and 54.53 U/min, respectively. At the experimental concentration, the activity of Malus domeri（Bois） Chev. PPO was inhibited by five different inhibitors. The inhibition of PPO by sodium chloride was the weakest, and the inhibitory effect of citric acid was better than that of EDTA, ascorbic acid and oxalic acid at higher concentration.
作者
郭兵兵
叶志青
黄欣欣
文良娟
GUO Bing-bing YE Zhi-qing HUANG Xin-xin WEN Liang-juan(College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, Chin)
出处
《保鲜与加工》
CAS
北大核心
2017年第4期20-24,共5页
Storage and Process
基金
广西科学研究与技术开发计划项目(桂科能1347017-2-6)
广西高校"广西特色农产品精深加工及安全控制"重点实验室项目
关键词
大果山楂
多酚氧化酶
酶学特性
Malus domeri（Bois） Chev.
polyphenol oxidase
enzymological characteristics
