Timmermans R A H, Mastwijk H C, Nierop Groot M N, Van Boekel M A J S
Wageningen Food & Biobased Research, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
Wageningen Food & Biobased Research, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
Int J Food Microbiol. 2017 Dec 18;263:47-60. doi: 10.1016/j.ijfoodmicro.2017.10.001. Epub 2017 Oct 2.
Application of mild (non)-thermal processing technologies have received considerable interest as alternative to thermal pasteurisation, because of its shorter holding time and lower temperature aiming for an improved product quality. To understand and develop these alternative technologies, like pulsed electric fields, a proper comparison between the conventional thermal and alternative process is necessary. Up to recent, no suitable models were available to predict the inactivation of micro-organisms by a thermal process at a chosen short holding time, due to non-linearity. The recently developed Gauss-Eyring model with two variables temperature and time has the properties to be a suitable model to apply for short holding times, and was tested for this purpose. Therefore, this study aims to validate if the Gauss-Eyring model can be used to describe non-linear isothermal (a fixed temperature with varying holding time) and isotime (a fixed holding time with varying temperature) thermal inactivation data, and if it is a suitable model to predict the thermal inactivation as a function of temperature for short holding times. Inactivation data of Escherichia coli, Listeria monocytogenes, Lactobacillus plantarum, Salmonella Senftenberg and Saccharomyces cerevisiae in orange juice were collected via isothermal and isotime inactivation kinetics. Survival of the tested micro-organisms was modelled with the Gauss-Eyring model, which contains three parameters σ, Tr and Z. The transition of 'no inactivation' to 'inactivation' (i.e. the 'shoulder' in inactivation curves) can be characterised as the temperature-time (T,t) combination where T=Tr-Z·log(t), with Tr as the reference temperature defined for 1s treatment, Z as the temperature needed for a 10-fold increase of decrease of the holding time t, and σ as the temperature width of the distribution. The Gauss-Eyring model fitted well to the experimental data, and revealed different sensitivity for the tested micro-organisms. Based on the parameter estimations, survival curves for the desired short holding times were predicted.
温和（非）热加工技术作为热巴氏杀菌的替代方法受到了广泛关注，因为其保持时间较短且温度较低，旨在提高产品质量。为了理解和开发这些替代技术，如脉冲电场，有必要对传统热加工和替代加工进行适当比较。直到最近，由于非线性，还没有合适的模型可用于预测在选定的短保持时间内热加工对微生物的灭活情况。最近开发的具有温度和时间两个变量的高斯-艾林模型具有适用于短保持时间的特性，并为此进行了测试。因此，本研究旨在验证高斯-艾林模型是否可用于描述非线性等温（固定温度，保持时间可变）和等时（固定保持时间，温度可变）热灭活数据，以及它是否是预测短保持时间内热灭活随温度变化的合适模型。通过等温及等时灭活动力学收集了橙汁中大肠杆菌、单核细胞增生李斯特菌、植物乳杆菌、森夫滕贝格沙门氏菌和酿酒酵母的灭活数据。用包含三个参数σ、Tr和Z的高斯-艾林模型对受试微生物的存活情况进行建模。“无灭活”到“灭活”的转变（即灭活曲线中的“肩部”）可表征为温度-时间（T，t）组合，其中T = Tr - Z·log(t)，Tr为定义的1秒处理的参考温度，Z为保持时间t增加或减少10倍所需的温度，σ为分布的温度宽度。高斯-艾林模型与实验数据拟合良好，并显示出受试微生物的不同敏感性。基于参数估计，预测了所需短保持时间的存活曲线。
