Research and Development Division, Kewpie Corporation 5-13-1, Sumiyoshi-cho, Fuchu-shi, Tokyo 183-0034, Japan.
J Food Prot. 2013 Sep;76(9):1549-56. doi: 10.4315/0362-028X.JFP-12-524.
The growth kinetics of Listeria monocytogenes and natural flora in commercially produced pasteurized liquid egg was examined at 4.1 to 19.4°C, and a growth simulation model that can estimate the range of the number of L. monocytogenes bacteria was developed. The experimental kinetic data were fitted to the Baranyi model, and growth parameters, such as maximum specific growth rate (μ(max)), maximum population density (N(max)), and lag time (λ), were estimated. As a result of estimating these parameters, we found that L. monocytogenes can grow without spoilage below 12.2°C, and we then focused on storage temperatures below 12.2°C in developing our secondary models. The temperature dependency of the μ(max) was described by Ratkowsky's square root model. The N(max) of L. monocytogenes was modeled as a function of temperature, because the N(max) of L. monocytogenes decreased as storage temperature increased. A tertiary model of L. monocytogenes was developed using the Baranyi model and μ(max) and N(max) secondary models. The ranges of the numbers of L. monocytogenes bacteria were simulated using Monte Carlo simulations with an assumption that these parameters have variations that follow a normal distribution. Predictive simulations under both constant and fluctuating temperature conditions demonstrated a high accuracy, represented by root mean square errors of 0.44 and 0.34, respectively. The predicted ranges also seemed to show a reasonably good estimation, with 55.8 and 51.5% of observed values falling into the prediction range of the 25th to 75th percentile, respectively. These results suggest that the model developed here can be used to estimate the kinetics and range of L. monocytogenes growth in pasteurized liquid egg under refrigerated temperature.
研究了商业巴氏杀菌液态蛋中单核细胞增生李斯特菌和天然菌群的生长动力学，在 4.1 至 19.4°C 下进行，并开发了一种可估计单核细胞增生李斯特菌数量范围的生长模拟模型。实验动力学数据拟合到 Baranyi 模型，并估计了生长参数，如最大比生长速率（μ(max)）、最大种群密度（N(max)）和滞后时间（λ）。通过估计这些参数，我们发现单核细胞增生李斯特菌在 12.2°C 以下不会腐败生长，因此我们专注于开发二次模型时低于 12.2°C 的储存温度。μ(max)的温度依赖性由 Ratkowsky 的平方根模型描述。单核细胞增生李斯特菌的 N(max)被建模为温度的函数，因为随着储存温度的升高，单核细胞增生李斯特菌的 N(max)减少。使用 Baranyi 模型和 μ(max)和 N(max)二次模型开发了单核细胞增生李斯特菌的三级模型。使用蒙特卡罗模拟假设这些参数具有遵循正态分布的变化，模拟了单核细胞增生李斯特菌的数量范围。在恒定和波动温度条件下进行的预测模拟显示出很高的准确性，均方根误差分别为 0.44 和 0.34。预测范围似乎也显示出合理的良好估计，分别有 55.8%和 51.5%的观察值落入第 25 至 75 百分位数的预测范围。这些结果表明，这里开发的模型可用于估计冷藏温度下巴氏杀菌液态蛋中单核细胞增生李斯特菌的动力学和生长范围。
