牛肉中单增李斯特菌的热失活模型

【目的】建立牛肉中单增李斯特菌的热失活动力学模型。【方法】将接种了3种不同血清型的单增李斯特菌混合菌液的牛肉分别在55℃、57.5℃、60℃、63℃、66℃和70℃进行热处理,在不同温度条件下单增李斯特菌数从109CFU/g下降至103CFU/g,其热失活曲线用修正的Gompertz模型进行了拟合;利用线性模型对单增李斯特菌的相对失活率(μ)和所持续时间(M)的自然对数值与温度(55℃-70℃)进行拟合;通过在59℃和64℃对牛肉中单增李斯特菌热处理,对所建的模型进行了验证。【结果】建立了牛肉中单增李斯特菌热失活动力学的一级模型和二级模型,经验证其准确因子和偏差因子均在可接受范围内。【结论】本研究所建立的模型能较好的模拟不同温度(55℃-70℃)对牛肉中单增李斯特菌热失活的影响。

Thermal inactivation model of Listeria monocytogenes in ground beef

[Objective ]To set up suitable kinetic models for the evaluation of heat inactivation rate of Listeria monocytogenes in ground beef.[Methods]Ground beef,inoculated with 3 strains of L.monocytogenes,was subjected to heating at 55℃,57.5℃,60℃,63℃,66℃ or 70℃ to develop the isothermal kinetic models.The survival curves were fitted with modified Gompertz model after the bacterial counts were decreased from 109CFU /g to 103CFU /g.Natural logarithm of μ(the relative inactivation rate) and M(time constant) were fitted with linear regression model.The kinetic models were validated at 59℃ and 64℃.[Results]We established one first-level model and one secondary-level model to predict the inactivation rate.In addition,we validated the accuracy and deviation of the models to guarantee their feasibility.[Conclusion]The models should be suitable for describing the survival of L.monocytogenes in ground beef at different temperatures,which are helpful for the control of the pathogens.