Quantitative Risk Assessment And Management On Cross-Contamination Of Listeria Monocytogenes During Chilled-Emulsified Sausage Processing

Listeria monocytogenes was one of the four major zoonotic foodborne pathogens,and it was taken as the research object in this article.The L.monocytogenes risk of chilled-emusified sausage was studied by predicted microbiology modelling.It could provide a theoretical reference for the research system of quantitative microbiological risk assessment?QMRA?and risk management.Firstly,different chopping methods and cleaning ways were studied to understand the transfer of L.monocytogenes.The chopping cross-contamination model may provide a useful tool in developing the meat product risk assessment.Moreover,the L.monocytogenes cross-contamination was studied during filling.A processing exposure assessment model of L.monocytogenes was established for chilled-emusified sausage,based on the L.monocytogenes cross-contamination during chopping and filling.Meanwhile,the morbidity probability of healthy people and susceptible population were fitted by 4 dose-response models,and the Weibull-Gamma model was obtained as the optimal model.Moreover,based on the L.monocytogenes risk assessment,the food safety objective?FSO?of chilled-emusified sausage was set by prevalence-dose?PD?curve.In addition,other food safety standards were established to provide tools for L.monocytogenes risk management,such as performance objective?PO?,performance criterion?PC?,and microbiological criteria?MC?.The detailed contents and conclusions were list as follows:Firstly,the effect of chopping methods and cleaning ways on L.monocytogenes cross-contamination was explored.The cross-contamination model was developed by considering transfer rate only,and the modified one was established by taking both transfer rate and inactivated rate into account.Meanwhile,the general form of cross-contamination model was developed.Transfer rates of L.monocytogenes from pork sample to bowl chopper and the opposite direction were showed significant differences?p<0.05?,and M₃ was chose as the optimal chopping method.Moreover,not only the determination coefficient R² of the modified cross-contamination model was high and the root mean square error was low,but also the accuracy factor A_f and the deviation factor B_f about the model were within the acceptable range.The modified model was used to predict the L.monocytogenes cross-contamination under low inoculum levels.The contamination level of L.monocytogenes was estimated to have a mean value of 0.37 log CFU/g to 1.11 log CFU/g with a 90%confidence interval under control group,and higher than contamination levels treated by three cleaning methods.Secondly,the exposure assessment model of L.monocytogenes was developed from factory to retail,and the dose-response models were used to predict the morbidity probability of customers.The experimental results demonstrated that the transfer rate was higher from equipment to meat sample than the opposite direction,and the difference was significant?p?0.05?.For example,when the dose of healthy people was6 log CFU,the predicted morbidity rate of Weibull-Gamma model?30%?was higher than the predicted incidence rate of Exponential model?0?,Beta-Poisson model?10%?and Log-Logistic model?0?,respectively.In addition,the predicted morbidity rate of healthy people was lower without considering L.monocytogenes cross-contamination.The similar result was acquired from the susceptible population.Moreover,the Weibull-Gamma model was used to predict the morbidity rate of healthy people and susceptible population at sausage consumption,and logistic?0.42,0.08?and logistic?0.46,0.08?were the best distributions after fitting,respectively.The QMRA of chilled-emusified sausage could apply to optimize the frame of pathogenic bacteria risk assessment in meat product,and improve the prediction accuracy for the morbidity rate of customers.Thirdly,food safety standards were established to manage the L.monocytogenes contamination during chilled-emusified sausage processing.The FSO of chilled-emusified sausage was set as 0.36 log CFU/g based on the L.monocytogenes cross-contamination during chopping and filling,while the other FSO was set as-4.58log CFU/g without considering cross-contamination.The established PO and PC were more integrated based on cross-contamination.According to the result of OC curve,the sampling plan and MC were more normlized based on cross-contamination.In addition,the risk of customer was overestimated,while the risk of producer was underestimated without considering cross-contamination.In summary,the cross-contamination model of L.monocytogenes was established during chopping.Moreover,the QMRA and risk management of L.monocytogenes were developed for chilled-emusified sausage,respectively.Meanwhile,this research could provide a reference for understanding the L.monocytogenes transfer during chopping,reducing the morbidity rate of customer,and improving the research system of microbial risk assessment and risk management.