Abstract Understanding the thermal inactivation of biopreservatives in food matrixes is essential for their proper use in the food industry, enabling reduction of heating time and optimization of heating temperature. With this aim in mind, the effect of heat treatment on the activity and thermostability of commercial nisin from Lactococcus lactis was investigated. Residual activity tests performed for 90 min in the 70–86 °C temperature range at pH 3.0 demonstrated that bacteriocin thermoinactivation followed first-order kinetics. Low values of the inactivation rate constant (0.0089–0.0892 min−1) and high values of the decimal reduction time (25.8 ≤ D-value ≤ 258.4 min) indicated excellent nisin thermostability in the lower end of the investigated temperature range, but the thermal resistance constant (z-value) was only 15.4 °C, which pointed out poor thermoresistance at the higher end. Thermodynamic parameters estimated for nisin irreversible thermal inactivation were energy, enthalpy and Gibbs free energy of activation of 155.1, 152.2–152.3 and 83.5–86.6 kJ mol−1, respectively, and activation entropy of 188.6–192.5 J mol−1 K−1. If on the one hand these results taken together confirm the thermostability of nisin as a biopreservative in use in the food industry, on the other hand suggest the importance of looking for new more thermostable antimicrobials to use in operations at higher temperatures.

中文翻译：

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乳酸链球菌肽热灭活的动力学和热力学参数

摘要 了解食品基质中生物防腐剂的热灭活对于它们在食品工业中的正确使用至关重要，能够减少加热时间和优化加热温度。考虑到这一目标，研究了热处理对来自乳酸乳球菌的商品化乳酸链球菌肽的活性和热稳定性的影响。在 pH 3.0、70-86 °C 温度范围内进行 90 分钟的残留活性测试表明，细菌素热灭活遵循一级动力学。失活速率常数的低值 (0.0089–0.0892 min-1) 和十进制还原时间的高值 (25.8 ≤ D 值 ≤ 258.4 分钟) 表明在研究温度范围的低端具有出色的乳酸链球菌肽热稳定性，但热稳定性电阻常数（z 值）仅为 15.4 °C，这指出了高端的耐热性差。为乳链菌肽不可逆热失活估计的热力学参数分别为 155.1、152.2-152.3 和 83.5-86.6 kJ mol-1 的能量、焓和吉布斯自由能，以及 188.6-192.5 J mol-1 K-1 的活化熵。如果一方面这些结果综合起来证实了乳酸链球菌肽作为食品工业中使用的生物防腐剂的热稳定性，另一方面表明寻找新的更耐热的抗菌剂以用于更高温度的操作的重要性。5 J mol−1 K−1。如果一方面这些结果综合起来证实了乳酸链球菌肽作为食品工业中使用的生物防腐剂的热稳定性，另一方面表明寻找新的更耐热的抗菌剂以用于更高温度的操作的重要性。5 J mol−1 K−1。如果一方面这些结果综合起来证实了乳酸链球菌肽作为食品工业中使用的生物防腐剂的热稳定性，另一方面表明寻找新的更耐热的抗菌剂以用于更高温度的操作的重要性。