Table 9.

Sources of uncertainty associated with the AQs and their possible impact on the conclusions

Source of uncertainty	Cause of the uncertainty	Impact of the uncertainty on the conclusions (e.g. over/underestimation)
Identification of viral hazards	All viral hazards that may occur in the raw materials for production of pig PAP may not have been identified through the literature search. It is also possible that the occurrence of virus, in general, or certain families, in particular, have never been investigated in materials used for pig PAP production.	The lack of identification of a relevant virus is expected to impact the conclusions only if it would be a heat‐resistant virus (e.g. non‐enveloped DNA viruses). Parvoviruses are included in the assessment and are considered among the most heat‐resistant viruses in nature, and it is unlikely that other more heat‐resistant viruses, not considered in the opinion, could occur.
Technical parameters for methods 2 to 5	The Commission Regulation (EU) 142/2011 specifies that the core temperatures listed under each method must be achieve. Either in batch or continuous mode, the temperature in different sections of the equipment must be higher in order to ensure the minimum temperatures at the core.	As estimates were made considering core temperatures being achieved, the level of inactivation achieved by processing methods 2 to 5 may be in some cases underestimated outside the core.
Technical parameters for method 7	Method 7 requires compliance with microbiological criteria ensuring the non detection of Salmonella and Clostridium perfringens, and certain levels of Enterobacteriaceae, but processes approved in the EU since 2004 for method 7 have very different parameters in terms of temperature and time combinations.	Depending on the method applied, the inactivation of the indicator microorganisms in the raw material could be higher or lower than that calculated for the five scenarios included in the present opinion.
Data related. Identification of studies on the inactivation of the hazards	Relevant records for extraction of data on thermal inactivation of selected indicators were identified through literature searches. There is the possibility that some relevant studies were not identified or considered for data extraction.	Considering the randomness of the non‐inclusion of potentially relevant studies, this source of uncertainty could lead to either an over or underestimation of the inactivation of the biological hazards.
Data related. Type of matrices used for the evaluation of the inactivation of the hazards	The data extracted on the thermal inactivation of hazards were sourced from experimental studies using different matrices, in most cases of a different nature to the materials used for pig PAP production. The different composition in terms of dry matter (total solid contents, aw), fat content, etc. determines the capacity of hazards to survive under different conditions of time/temperature.	The ability of methods 2 to 5 and method 7 to achieve the targeted reductions in the materials used to produce pig PAP may be higher or lower than estimated. Most inactivation data used were derived from studies using liquid media or foods. As microbial inactivation by heat is lower in systems with lower aw, estimations from studies on liquid acidic media or on foods with high aw, this could result in an overestimation of the inactivation achieved by methods 2 to 5 and method 7.
Data related. Strain of the hazard and enumeration method used to assess the level of inactivation of the hazards	The data extracted on the thermal inactivation of hazards were sourced from experimental studies using specific strains/isolates of the relevant hazards and different analytical methods, which, for viral hazards, are not standardised. It is uncertain whether those strains are representative of the behaviour of the whole species.	This source of uncertainty could lead to either over or underestimate the inactivation of the biological hazards.
Data related. Temperature measurement used for the inactivation of the hazards	In the studies, the temperature was measured in the substrate and resembled isothermal conditions. The accuracy of the temperature measurement may affect the thermal resistance estimation.	This source of uncertainty could lead to either an over or underestimation of the inactivation of the biological hazards.
Data related. Heating temperatures used for the inactivation of the hazards	The data retrieved on thermal inactivation of hazards contained information on certain heating temperatures, that in some cases were far from the temperatures under assessment. Extrapolations at temperatures above those for which experimental data was available were not performed.	No extrapolation at temperatures above those for which experimental data is available may lead to an underestimation of the level of inactivation achieved by the methods, especially for those methods that work at higher regime temperatures.
Model related. D‐value estimation	Estimation of D values from primary research studies. D values were extracted, where available, from tables and text as in the published peer‐reviewed literature without checking the primary data. For viruses, D values from data with low linearity and point estimates of time to 1 log10 reduction at different temperatures were also included.	Underestimation or overestimation of D‐values could lead to overestimation or underestimation of log10 reductions. Uncertainty in D values introduces bidirectional uncertainty in the estimation of Dref and z.
Model assumptions	The model does not consider come up times. i.e. the additional inactivation due to heating and cooling times to the time/temperature combinations required for each process under assessment.	The model underestimates the level of inactivation achieved by each method, the underestimation being greater in the method/s with higher temperatures.
Use of Clostridium botulinum as surrogate for Clostridium perfringens	Use of thermal resistance data of C. botulinum spores, obtained in different substrates, conditions and methodologies, assuming that they will be, at least, equivalent to the thermal inactivation of C. perfringens spores in the conditions of the method evaluated.	Using D values at temperatures below those of some of the assessed methods (e.g. method 4 and method 7 scenarios 4 and 5) could lead to underestimation of the level of inactivation achieved.
Use of comparative analysis with Clostridium botulinum in the EKE	In the EKE both the model results and the results of the accumulated lethality in minutes at Tref 121°C of methods 2 to 5 and the scenarios of method 7, at temperature other than the reference one for C. botulinum (121.1°C), were used.	For some of the methods there was a discrepancy between the outputs of the model and of the EKE. The individual judgements may have over or underestimated the level of inactivation of the methods.