Laboratory of Food Technology, Faculty of Agricultural Science, Katholieke Universiteit Leuven, Belgium.
Biotechnol Bioeng. 1992 Jul;40(3):396-402. doi: 10.1002/bit.260400309.
In view of a possible application of the alpha-amylase from Bacillus licheniformis as a time-temperature integrator for evaluation of heat processes,(11) thermal inactivation kinetics of the dissolved and covalently immobilized enzyme were studied in the temperature range 90-108 degrees C. The D-values (95 degrees C) for inactivation of alpha-amylase, dissolved in tris-HCl buffer, ranged from 6 to 157 min, depending on pH, ionic strength, and Ca(2+) and enzyme concentration. The z-value fluctuated between 6.2 and 7.6 degrees C. On immobilization of the alpha-amylase by covalent coupling with glutaraldehyde to porous glass beads, the thermoinactivation kinetics became biphasic under certain circumstances. For immobilized enzyme, the D-values (95 degrees C) ranged between 17 and 620 min, depending largely on certain environmental conditions. The z-value fluctuated between 8.1 and 12.9 degrees C. In each case of biphasic inactivation, the z-value of the stable fraction (with the higher D-values) was lower than the z-value of the labile fraction.
鉴于地衣芽孢杆菌α-淀粉酶可能作为评估热加工过程的时间-温度积分器的应用，（11）研究了溶解态和共价固定化酶在 90-108°C 温度范围内的热失活动力学。在 tris-HCl 缓冲液中溶解的α-淀粉酶的 D 值（95°C）取决于 pH 值、离子强度以及 Ca(2+)和酶浓度，范围为 6 至 157 分钟。z 值在 6.2 至 7.6°C 之间波动。当α-淀粉酶通过与多孔玻璃珠的共价偶联固定化时，在某些情况下，热失活动力学呈两相性。对于固定化酶，D 值（95°C）在 17 至 620 分钟之间变化，这主要取决于某些环境条件。z 值在 8.1 至 12.9°C 之间波动。在两相失活动力学的每种情况下，稳定部分（具有较高 D 值）的 z 值低于不稳定部分的 z 值。
