盐水鸭中单核细胞增生李斯特菌生长预测模型的建立

为研究盐水鸭中单核细胞增生李斯特菌(Listeriamonocytogenes,Lm)的生长规律,通过测定4、10、16、25℃条件下的生长数据,选用4种常用的一级模型(Gompertz、Logistic、Richards及MMF模型)对数据进行拟合,比较各模型决定系数R^2和均方误差(MSE),确定最适一级模型,根据一级模型得到的最大比生长速率(μmax)和迟滞期(λ)建立与温度相关的二级模型。结果表明:Gompertz模型拟合的生长曲线R^2均达到0.99以上,为最适一级模型,在25℃条件下,Lm经0.78 h后即进入对数期,从4℃提高到10℃时,生长速率从0.02 1g(cfu/g)·h^-1增至0.05 1g(cfu/g)·h^-1,说明温度对盐水鸭中Lm的生长影响较大。选用Ratkowsky平方根模型建立的温度与μmax关系的二级模型R^2为0.98,偏差因子(Bf)、准确因子(Af)分别为0.99、1.01,二次多项式模型建立的温度与λ关系的R^2为0.99,Bf、Af分别为1.01、1.08,表明所建两种模型均能较好地描述盐水鸭中Lm的生长情况。本研究建立的生长模型可为监控盐水鸭的食品安全和风险评估提供参考。

Establishment of Growth Predictive Model for Listeria monocytogenes in Salted-duck

To investigate the growth of Listeria monocytogenes in salted-duck, the four commonly used primary growth dynamics models(Gompertz model, Logistic model, Richards model and MMF model) were used to fit the growth curve of Listeria monocytogenes by determining the growth data at 4 ℃, 10 ℃, 16 ℃ and 25 ℃, respectively. By comparing the determination coefficients(R^2) and mean square error(MSE) of each model, the optimal primary growth model was determined. The maximum specific growth rate(μmax) and lag phase(λ) obtained by the primary model were used to establish a temperature-dependent secondary model. The results showed that the growth curve R^2 of the Gompertz model was above 0.99, which was the most suitable primary model for the growth of Listeria monocytogene. At 25 ℃, Listeria monocytogenes entered the logarithmic period after 0.78 h. When temperature increased from 4 ℃ to 10 ℃, the growth rate of Listeria monocytogenes in salted duck increased from 0.02 1 g(cfu/g).h^-1 to 0.05 1 g(cfu/g).h^-1, indicating that temperature had a greater impact on the growth of Listeria monocytogenes in salted ducks. The R^2 of the relationship between temperature and μmax established by Ratkowsky square root model was 0.98, and the deviation factor(Bf) and accuracy factor(Af) were 0.99 and 1.01, respectively. The R^2 of the relationship between temperature and λ established by the quadratic polynomial model was 0.99, and the Bf and Af were 1.01 and 1.08, respectively. The results showed that the secondary model could describe the growth of Listeria monocytogenes in salted-duck with satisfaction. This study will provide a reference for the food safety and the risk assessment of Listeria monocytogenes in salted-duck.