Food Process Engineering and Dairy Technology, Research Center for Nutrition and Food Sciences-ZIEL, Department Technology, TU München, Weihenstephaner Berg 1, 85354 Freising, Germany.
Cryobiology. 2012 Dec;65(3):308-18. doi: 10.1016/j.cryobiol.2012.08.005. Epub 2012 Sep 3.
The aim of this work was to describe the temperature dependence of microbial inactivation for several storage conditions and protective systems (lactose, trehalose and dextran) in relation to the physical state of the sample, i.e. the glassy or non-glassy state. The resulting inactivation rates k were described by applying two models, Arrhenius and Williams-Landel-Ferry (WLF), in order to evaluate the relevance of diffusional limitation as a protective mechanism. The application of the Arrhenius model revealed a significant decrease in activation energy E(a) for storage conditions close to T(g). This finding is an indication that the protective effect of a surrounding glassy matrix can, at least, partly be ascribed to its inherent restricted diffusion and mobility. The application of the WLF model revealed that the temperature dependence of microbial inactivation above T(g) is significantly weaker than predicted by the universal coefficients. Thus, it can be concluded that microbial inactivation is not directly linked with the mechanical relaxation behavior of the surrounding matrix as it was reported for viscosity and crystallization phenomena in case of disaccharide systems.
这项工作的目的是描述在几种储存条件和保护系统（乳糖、海藻糖和葡聚糖）下，与样品的物理状态（玻璃态或非玻璃态）相关的微生物失活动力学的温度依赖性。通过应用 Arrhenius 和 Williams-Landel-Ferry（WLF）两种模型来描述得到的失活动力学常数 k，以评估扩散限制作为一种保护机制的相关性。Arrhenius 模型的应用表明，在接近玻璃化转变温度（Tg）的储存条件下，活化能 E(a)显著降低。这一发现表明，周围玻璃基质的保护作用至少可以部分归因于其固有的限制扩散和流动性。WLF 模型的应用表明，在 Tg 以上，微生物失活动力学的温度依赖性明显弱于通用系数预测的结果。因此，可以得出结论，微生物失活与周围基质的力学松弛行为没有直接联系，正如在双糖系统的粘度和结晶现象中报道的那样。
