Table C.6.

Potential sources of uncertainty identified in the assessment of the relative levels of exposure to selected pathogen(s) per serving through the consumption of industrially HPP‐treated in comparison to raw vs. thermally pasteurised vs. UHT‐treated milk or colostrum

Source or location of the uncertainty	Nature or cause of the uncertainty	Impact of the uncertainty on the conclusions (e.g. over/underestimation)
Log10 reductions achieved by HPP	Model to describe the pathogen‐specific log reductions achieved in HPP treated milk as a function of pressure and time	Over/under‐estimation of HPP efficacy
Variability in the number of bacteria per serving before HPP and thermal treatment	Probability distribution (Poisson) assumed to adequately describe the number of bacteria dispersed in milk before HPP or thermal treatment	Impact of this uncertainty (over/under‐estimation of the number of bacteria per serving) is low. Use of the Poisson distribution is justified by the homogeneous nature of the matrix in which bacteria are dispersed.
Variability in the number of bacteria per serving after HPP and thermal treatment	Probability distribution (Poisson) assumed to adequately describe the number of survived bacteria homogeneously dispersed in milk after HPP or thermal treatment. The assumption would not be valid if for any reason bacteria are present in form of clusters or anyway not homogeneously dispersed and alternative distributions would be more suitable.	Impact of this uncertainty (over/under‐estimation of the number of survived bacteria per serving) is low. The use of alternative distributions would translate in wider (or skewed) distributions of the final number of bacteria per serving, but the effect would be the same across all the scenarios of initial levels of contamination (N0) tested. Therefore, the overall conclusions in terms of efficacy would not be affected unless HPP has a distinct impact on the distribution of the cells in the treated milk (this cannot be assessed with available data).
Variability in the number of bacteria per serving after HPP and thermal treatment	Non‐uniform piezo‐protective effect of the matrix	Impact of this uncertainty (over/under‐estimation of the number of survived bacteria per serving) is low. Use of the Poisson distribution is justified by the homogeneous nature of the matrix in which bacteria are dispersed.
Number of bacteria ingested at consumption	Could not be modelled due to lack of pathogen‐specific data needed to model growth during storage after HPP	Inconclusive

HPP: high‐pressure processing.