Park K H, Fricker A
Z Ernahrungswiss. 1977 Jun;16(2):81-91. doi: 10.1007/BF02021483.
The thermal inactivation and storage behaviour for horseradish and spinach peroxidases were investigated in defined systems, in spinach also within its natural environment. The inactivation curves of either enzyme show a sharp bend which is clearly visible at low, but not at higher temperatures. The D-values were taken from the inactivation curves. z-values resulting from the D-values were 25.5 degrees C for horseradish peroxidase, 13 degrees C for isolated peroxidase and 18 degrees C for peroxidase in spinach extract. Horseradish peroxidase was relatively heat-resistent at pH 6.0, spinach peroxidase at pH 5.0-6.0; both enzymes were found to be highly susceptible to heat at pH 4.0. Peroxidase isolated from spinach responded differently to heating than the enzyme in spinach extract or suspension. This discrepancy indicates that certain model experiments cannot be transferred to foods. Heated peroxidase from horseradish and spinach were found to regenerate during storage; the extent of regeneration depended on the pH.
在特定体系中研究了辣根过氧化物酶和菠菜过氧化物酶的热失活及储存行为，对于菠菜过氧化物酶还研究了其在自然环境中的情况。两种酶的失活曲线均呈现出一个明显的拐点，该拐点在低温下清晰可见，而在较高温度下则不明显。D值取自失活曲线。由D值得出的z值，辣根过氧化物酶为25.5℃，分离出的过氧化物酶为13℃，菠菜提取物中的过氧化物酶为18℃。辣根过氧化物酶在pH 6.0时相对耐热，菠菜过氧化物酶在pH 5.0 - 6.0时耐热；发现两种酶在pH 4.0时对热高度敏感。从菠菜中分离出的过氧化物酶与菠菜提取物或悬浮液中的酶对加热的反应不同。这种差异表明某些模型实验不能直接应用于食品。发现辣根和菠菜经加热的过氧化物酶在储存期间会再生；再生程度取决于pH值。
