A QMRA Model for Salmonella in Pork Products During Preparation and Consumption

Abstract

As part of a quantitative microbiological risk assessment (QMRA) food chain model, this article describes a model for the consumer phase for Salmonella-contaminated pork products. Three pork products were chosen as a proxy for the entire pork product spectrum: pork cuts, minced meat patties, and fermented sausages. For pork cuts cross-contamination is considered the most important process and therefore it is modeled in detail. For minced meat, both cross-contamination and undercooking are the relevant processes. For those commodities bacterial growth during transport and storage is also modeled. Fermented sausages are eaten raw and the production may be defective. Variability between consumers' behavior and the impact of variability between production processes at the farm and abattoir are taken into account. Results indicate that Salmonella levels on products may increase significantly during transport and storage. Heating is very efficient at lowering concentrations, yet cross-contamination plays an important role in products that remain contaminated. For fermented sausage it is found that drying is important for Salmonella reduction. Sensitivity analysis revealed that cross- contamination factors "knife cleaning" and "preparation of a salad" are important parameters for pork cuts. For minced meat cleaning of the board, salad consumption, refrigerator temperature, and storage time were significant.

Can stochastic consumer phase models in QMRA be simplified to a single factor?

“…These CPMs are part of a full risk assessment model for Salmonella in the pork production chain in selected European Union member states (Hill et al, 2011;Swart et al, 2016;Snary et al, 2016). In this model three types of pork meat are considered: minced pork, pork cuts and fermented sausages.…”

“…As in Swart et al (2016), portion sizes Ws are fixed at 146 g for pork cuts and 125 g for minced meat, so the initial number of cfu per portion N0 = Cret × Ws. Both CPMs, for pork cuts and minced meat, as described by Swart et al 2016, consider three processes: transport and storage, preparation and heating, and are presented in Figure 1. The transport and storage process is modelled identically for both products.…”

“…where Ttr, Tst, ttr and tst are the randomly sampled temperature (T) and time (t) during transport (tr) and storage (st), using the same distributions as Swart et al (2016). Preparation and heating are modelled differently in both Salmonella CPMs:…”

“…The transport and storage process is modelled identically for both products. Swart et al (2016) use Baranyi's dynamic growth model. As it is difficult to apply this specific model in @Risk and the specific choice of the growth model is not of great importance for our purposes, we apply an exponential growth model as a primary growth model and a square root model for the temperature (Ratkowsky 1982) as a secondary growth model in this study:…”

“…For Salmonella in pork, we used two CPMs based on Swart et al (2016). These CPMs are part of a full risk assessment model for Salmonella in the pork production chain in selected European Union member states (Hill et al, 2011;Swart et al, 2016;Snary et al, 2016).…”