单增李斯特菌在冷鲜猪肉中的生长预测模型比较

Comparison of growth models of Listeria monocytogenes in chilled pork

摘要:

摘要:【目的】探讨单增李斯特菌(Listeria monocytogenes，LM) 在冷鲜猪肉中的生长及现有预测软件GP(Growth Predictor)、PMP (Pathogen Modeling Programme) 及CP (ComBase Predictor) 对LM 在冷鲜猪肉中生长的预测准确性。【方法】测定LM 在4℃、8℃、12℃及16℃冷鲜猪肉中的生长，并用DMFit 软件对生长数据进行拟合，计算各个温度点下的迟滞期( Lag phase duration，LPD)、生长率(Growth rate，GR)、最大生长密度(Maximum population density，MPD)，同时用3 种预测模型对相同条件下LM 在猪肉中的生长进行预测，将实测值与预测值进行比较分析。【结果】冷鲜猪肉在16℃，经过2. 6h LM 即进入对数生长期。从8℃ 提高至12℃时，LM 在冷鲜猪肉中的生长率从0. 017log(cfu/g)．h－1增至0.038log(cfu/g)．h－1。在4℃－16℃，PMP预测的GR 要比实测值低，而LPD 则高于实测值。GP 在8℃ 及以上的温度范围内，所预测LPD 比实测值偏高。3 种预测模型中，GP 对GR 的预测稍高于实测值，偏差因子(Bf)为1.01，准确因子(Af)为1.38;CP对LPD 的预测值与实测值更为接近，Af及Bf分别为4.33及2.83。【结论】在冷鲜猪肉生产和销售过程中，严格控制温度尤为重要。PMP 的预测较为保守，不适于冷鲜猪肉中LM 生长的预测;建议用GP对GR进行预测，而CP 对LPD 的预测仅作为参考。

Abstract:

Abstract:［Objective］To investigate the growth of Listeria monocytogenes (LM) in chilled pork at four temperature and to evaluate the accuracy of three predictive models- GP (Growth Predictor)，PMP(Pathogen Modeling Programme) and CP (ComBase Predictor) in predicting LM growth in chilled pork． ［Methods］ LM growth in chilled pork at 4℃，8℃，12℃ and 16℃ were determined by plate counting． The growth data were fitted by DMFit software to calculate related growth parameters: lag phase duration (LPD)，growth rate (GR) and maximum population density (MPD)．The observation values and predictions of the three different models were compared． ［Result］LM grew into exponential phase after 2. 6 hours of adaptation at 16℃ ． A four- degree increase from 8℃ to 12℃ doubled GR from 0.017 log(cfu/g)．h－1 to 0.038log(cfu/g)．h－1)．Over the temperature span from 4℃ to 16℃，GR values predicted by PMP were lower than observations，while those of LPD higher than observations． At temperature above 8℃ ，LPD values predicted by GP were higher than observations．Of three predictive models，GP prediction of GR was the best，though slightly higher than observations，with the bias factor (Bf) at 1.01 and accuracy factor (Af) at 1. 38，while CP was nearest to observations for LPD prediction，but still with high values of Af and Bf (4.33 and 2.83 respectively)．［Conclusion］ It is of utmost importance to control temperature in chilled pork production and distribution． Because of the conservative but unsafe predictions，PMP model is not suitable for prediction of LM in chilled pork． We suggest to use GP for GR prediction． CP may be used to predict LPD as a reference，but with caution．