We derived three distinct modeling approaches, designated henceforth as method #1, #2 and #3.
2.1.1. Method #1
This approach tracks bacterial concentrations in food units. At step j of the modeled food-production pathway, contamination of the food units is characterized by: i) prevalence Pj, defined as the proportion of food units with a mean bacterial concentration
>0 cfu/g, and ii) mean bacterial level Cj in the contaminated food units, modeled as some rational number (e.g. -1.23, or 2.5; unit: log10 cfu/g). ). As an illustrative example, consider food units contaminated at a given step of the pathway with Pj ¼ 10% and Cj ¼ -1.22 log10 cfu/g (i.e., 6 cfu in 100 g).