摘要
杏子多酚氧化酶是造成杏子果肉褐变的主要因素,研究其动力学特性对杏子深加工中防止果肉褐变有着重要理论意义。采用分光光度计法研究pH、温度、抑制剂和高压二氧化碳处理对杏子多酚氧化酶性质的影响,结果表明:杏子(品种为色买提)的最适底物为邻苯二酚,最适pH5.0,最适温度40℃。多酚氧化酶催化的酶促褐变反应动力学符合米氏方程,该酶促反应的动力学常数Km为0.014mol/L,最大速率为287U/min。控制pH3.0以下,或者采用L-抗坏血酸4mmol/L与柠檬酸8mmol/L复配,或采用高压二氧化碳40MPa处理30min都可以将相对酶活性控制在20%以下;温度90℃处理6min以上或100℃处理4min可以完全抑制酶活性。在实际应用中,可根据产品特性不同选用适宜的处理方法或组合抑制褐变。
Polyphenol oxidase is the main factor causing the flesh browning of apricot.Studying on its kinetic characterization has great theoretical significance to further processing of apricot.Effects in different conditions of pH,temperature,inhibitors and high pressure carbon dioxide was determined by the spectrophotometric method.The result showed that its optimum pH value and temperature are 5.0 and 40 ℃ based on substrate of catechol.The kinetics of the enzyme-catalyzed reaction of PPO is in accord with Michaelis-Menten equation,whereas Km and Vmax values are respectively 0.014 mol/L and 287 U/min.Any of treatment method could keep value of polyphenol oxidase relative activity lower than 20%：pH value below 3.0 combination of L-ascorbic acid 4 mmol/L and citric acid 8 mmol/L,or high pressure carbon dioxide at 40 MPa for 30 min.Furthermore,polyphenol oxidase activity was inhibited completely when temperature at 90 ℃ for 6 min or 100 ℃ for 4 min.In actual application,how to select suitable treatment methods should in the light of peculiarity of end-product requirement.
出处
《食品科技》
CAS
北大核心
2011年第8期69-72,76,共5页
Food Science and Technology
基金
北京市科技计划项目(D101105046210001)
关键词
杏子
多酚氧化酶
动力学
apricot
polyphenol oxidase
kinetic
