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This study aimed to evaluate a cross contamination model 1 for its capability of describing transfer of Salmonella spp. and L. monocytogenes during grinding of varying sizes and numbers of pieces of meats in two grinder systems. Data from 19 trials were collected. Three evaluation approaches were applied: i ) Acceptable Simulation Zone method compared observed with simulated transfer, ii ) each trial was fitted and parameters were integrated in a Quantitative Microbiological Risk Assessment model, iii ) the Total Transfer Potential was calculated from fitted parameters. Risk estimates revealed that grinding was influenced by sharpness of grinder knife, specific grinder and grinding temperature. [ABSTRACT FROM AUTHOR]

To enhance food safety, whole carcass decontamination during slaughter has been considered as a control measure to reduce pathogen concentrations on meat. The effect of such decontamination is usually measured in terms of the mean log reduction in concentration. However, the variation in this reduction may also contribute to the overall impact of the decontamination measure. Therefore, this study focuses on the relative contribution of mean and variation for the effect of decontamination in the slaughter-line expressed in terms of the effect on human health risk. A stochastic risk model is developed to assess the potential effects of pig carcass decontamination at the end of slaughter on the risk of salmonellosis for Danish consumers. Salmonella concentrations are represented by a lognormal distribution fitted to microbiological data, characteristic for Salmonella numbers on carcasses at the end-point of Danish slaughterhouses. Decontamination scenarios are represented by various gamma distributions with different means and standard deviations. The values chosen for these parameters are based on experimental data of the effect of real decontamination procedures applied to pork. Results show that the variation of decontamination has a relevant effect on risk reduction for the consumer: the higher the variation, the lower the overall risk reduction. This effect is particularly evident for procedures with a lower mean reduction (≤2.5 log 10 ), but less so for highly efficient decontamination procedures (>2.5 log 10 mean reduction). This difference is affected by the initial level of carcass contamination with Salmonella . With increasing mean and standard deviation of initial bacterial concentrations, it becomes increasingly relevant to account for the variation of the decontamination action, even if the mean decontamination effect is high. We conclude that for decontamination procedures with an overall mean reduction effect of 1–2 log 10 , it is important to consider the variation in effect: if the variation is large, the final effect of decontamination can be considerably smaller than expected on the basis of the mean only and efforts should be put in place to reduce the variation of the procedure. However, when a treatment of high mean reduction (>2.5 log 10 ) is used, the impact of variation becomes smaller and may be negligible. [ABSTRACT FROM AUTHOR]

Raw meat for sausage production can be contaminated with Salmonella . For technical reasons, meat is often frozen prior to mincing but it is unknown how growth of Salmonella in meat prior to freezing affects its growth potential during sausage fermentation. We investigated survival of exponential- and stationary-phase Salmonella Typhimurium (DT12 and DTU292) during freezing at − 18 °C and their subsequent growth potential during 72 h sausage fermentation at 25 °C. After 0, 7 and > 35 d of frozen storage, sausage batters were prepared with NaCl (3%) and NaNO 2 (0, 100 ppm) and fermented with and without starter culture. With no starter culture, both strains grew in both growth phases. In general, a functional starter culture abolished S. Typhimurium growth independent of growth phase and we concluded that ensuring correct fermentation is important for sausage safety. However, despite efficient fermentation, sporadic growth of exponential-phase cells of S. Typhimurium was observed drawing attention to the handling and storage of sausage meat. [ABSTRACT FROM AUTHOR]

Existing growth models and non-thermal survival models for Salmonella , Shiga-toxin producing Eschericia coli ( STEC ) and Listeria monocytogenes primarily focus on the static effect of a w , sodium nitrite (NaNO 2 ), pH and temperature. However, during the production of fermented sausages, the intrinsic factors and temperature change, and there is a need to develop models that can predict pathogen survival under dynamic conditions. The objective of this study was to develop a novel mathematical model for predicting survival of Salmonella , STEC and L . monocytogenes , taking into account the dynamics of the sausage environment during fermentation and maturation of fermented sausages. A total of 73 experiments were carried out in sausages containing different levels of NaCl in the water phase (WPS) (3.9–6.8%), NaNO 2 (0–200 ppm) and pH 48h (4.3–5.6). The minced meat was inoculated with approx. 10 6 cfu/g of a multi-strain cocktail of 3 strains of Salmonella ( S . Dublin, S . Typhimurium, S . Derby), 3 strains of STEC (O26:H-, O111:H- and O157) and five L . monocytogenes strains isolated from different meat products and environment. The sausages were fermented at 24 °C for 48 h using three different commercially available starter cultures followed by maturation at 16 °C until a weight loss of between 15% and 35% was achieved. Enumeration of Salmonella , STEC and L . monocytogenes was performed up to six times during fermentation and maturation, allowing for calculation of the log 10 reductions at each time point. The microbiological data, together with data for NaNO 2 and changes in pH and WPS, were used to develop the “ConFerm” tool, which consists of three separate partial least squares regression (PLS) models for predicting the reduction of Salmonella , STEC and L . monocytogenes , respectively, as a function of weight loss, pH decrease, NaNO 2 and WPS. The “ConFerm” tool was validated on a separate data set (n = 19). The Salmonella model had bias and accuracy factors of 1.02 and 1.15, the STEC model 1.04 and 1.24 and the L . monocytogenes model 0.99 and 1.27, respectively, indicating highly acceptable models. In conclusion, the models are applicable for predicting reduction of Salmonella , STEC and L . monocytogenes during the production of fermented sausages fermented at 24 °C and matured at 16 °C. The model has been made available to producers and other interested parties at http://dmripredict.dk (in English). [ABSTRACT FROM AUTHOR]

In a previous study, a model was developed to describe the transfer and survival of Salmonella during grinding of pork (Møller, C.O.A., Nauta, M.J., Christensen, B.B., Dalgaard, P., Hansen, T.B., 2012. Modelling transfer of Salmonella typhimurium DT104 during simulation of grinding of pork. Journal of Applied Microbiology 112 (1), 90–98). The robustness of this model is now evaluated by studying its performance for predicting the transfer and survival of Salmonella spp. and Listeria monocytogenes during grinding of different types of meat (pork and beef), using two different grinders, different sizes and different numbers of pieces of meats to be ground. A total of 19 grinding trials were collected. Acceptable Simulation Zone (ASZ), visual inspection of the data, Quantitative Microbiological Risk Assessment (QMRA), as well as the Total Transfer Potential (TTP) were used as approaches to evaluate model performance and to access the quality of the cross contamination model predictions. Using the ASZ approach and considering that 70% of the observed counts have to be inside a defined acceptable zone of ± 0.5 log 10 CFU per portion, it was found that the cross contamination parameters suggested by Møller et al. (2012) were not able to describe all 19 trials. However, for each of the collected grinding trials, the transfer event was well described when fitted to the model structure proposed by Møller et al. (2012). Parameter estimates obtained by fitting observed trials performed at different conditions, such as size and number of pieces of meat to be ground, may not be applied to describe cross contamination of unlike processing. Nevertheless, the risk estimates, as well as the TTP, revealed that the risk of disease may be reduced when the grinding of meat is performed in a grinder made of stainless steel (for all surfaces in contact with the meat), using a well-sharpened knife and holding at room temperatures lower than 4 °C. [ABSTRACT FROM AUTHOR]

Abstract: Salmonella can either be controlled pre-harvest, post-harvest or by a combination of both approaches. This paper describes the lessons learned in Danish Salmonella surveillance and control programme for finisher pigs and pork. Initially, main focus was on pre-harvest initiatives and correct identification of herds with respect to the risk for Salmonella that they represented. However, an analysis of risk-mitigating actions applied along the chain from stable to table showed that it would be more cost-effective to deal with Salmonella on the abattoirs than in the herds. This knowledge moved focus from pre- to post-harvest without giving up on pre-harvest surveillance. First of all, this meant increased attention on slaughter hygiene and individual interventions in the abattoirs. In brief, we learned that for a programme to be successful it must be based on standardised methods for sampling and testing to be able to evaluate and compare performance of the programme. More specifically, meat-juice samples taken from finisher pigs at the time of slaughter are an effective way of identifying high-risk herds for Salmonella. In addition, a penalty system might act as an incentive for farmers to deal with Salmonella in their herd. Additionally, common targets for all abattoirs allowing for unique control solutions should be adapted. Finally, decontamination techniques like hot water decontamination are a feasible way of dealing with high-risk pigs (Level-3 pigs). The current prevalence in Danish pork is around 1.2%, and a target is set to <1.0% to be reached by the end of 2013. The experience obtained by use of the Danish programme might be used to develop and implement appropriate types of surveillance programs as well as risk-mitigating measures in other countries. [Copyright &y& Elsevier]