Grijspeerdt Koen, Herman Lieve
Center of Agricultural Research, Department of Animal Product Quality, Ministry of Small Enterprises, Traders and Agriculture, Brusselsesteenweg 370, 9090 Melle, Belgium.
Int J Food Microbiol. 2003 Jan 26;82(1):13-24. doi: 10.1016/s0168-1605(02)00246-5.
A series of inactivation curves for Salmonella enteritidis were determined for boiling eggs using different conditions of time and temperature. No significant influence of egg weight could be found on the temperature evolution in the yolk. The inactivation curves consistently showed an initial slow decline in bacterial number at lower temperatures, after which a very rapid inactivation took place. It was not possible to reproduce this behavior using a traditional inactivation model. A pragmatic model existing in two parts was therefore constructed. When the temperature is below a certain threshold, the inactivation follows a second order temperature dependence. Above the temperature threshold, standard Bigelow inactivation kinetics are assumed. This model could describe the data reasonably well, provided that the decimal reduction time in the Bigelow model was assumed to be different for a fast or slow heating process, respectively. The results suggest that the bacteria are more resistant towards a slower heating process, which is confirmed by analyzing the raw data. A fail-safe model can be obtained by using the parameters associated with the slow heating process. The statistical properties of the calibrated model are satisfactory, and a cross-validation shows that it can be used for egg boiling conditions outside its calibration range.
针对肠炎沙门氏菌，在不同时间和温度条件下煮鸡蛋，测定了一系列的灭活曲线。未发现鸡蛋重量对蛋黄温度变化有显著影响。灭活曲线始终显示，在较低温度下细菌数量最初缓慢下降，之后迅速灭活。使用传统的灭活模型无法重现这种行为。因此构建了一个分为两部分的实用模型。当温度低于某个阈值时，灭活遵循二级温度依赖性。高于温度阈值时，假定为标准的毕氏灭活动力学。只要假定毕氏模型中的十进制减少时间在快速或慢速加热过程中分别不同，该模型就能较好地描述数据。结果表明，细菌对较慢的加热过程更具抗性，这通过分析原始数据得到了证实。通过使用与慢速加热过程相关的参数，可以获得一个故障安全模型。校准模型的统计特性令人满意，交叉验证表明它可用于其校准范围之外的煮鸡蛋条件。
