Microbe count in food can also be established by calculation
“The effect of microbiological criteria on consumer risk can be determined theoretically by means of samples taken in the production chain. Consequently, approval of the production lot for sale to consumers may be based on the measured concentrations of micro organisms and the assessment made on this basis”, says Jukka Ranta, Senior Researcher, PhD, of Evira.
By using this model, it is possible to compare optional sets of criteria and identify the optimum solution where the risk and cost are at a minimum. For example, this can be accomplished by adjusting the number of samples or the concentration levels applied to the samples. Additionally, the model can be used in conjunction with other information for determining how changes in the number of samples affect the accuracy of the assessment.
The study was carried out as an inter-Nordic project that drew upon Nordic data on campylobacter levels in broiler meat production.
Campylobacter is the main cause of gastrointestinal infection in humans in Europe. Typical sources of infection are undercooked meat, contaminated water or drinking water, raw milk or contact with animals. The risks vary from one country to another.
Evira’s task in the the project was to develop a Bayesian approach to the determination of microbiological levels in foods as a probability distribution based on samples.
The new model makes it possible to take into account the combined uncertainty of several factors related to the risk assessment, conditionally on the number of samples and analysis results.
“The uncertainty factors include the occurrence of production lots containing microbes and the prevalence of microbes within such production lots as well as the average microbe counts per gram throughout the entire production chain and within each individual lot in such occurrences. Variation in concentrations within and between lots is another uncertainty factor”, Ranta says.
Participating in the project along with Evira were the Technical University of Denmark, the National Veterinary Institute of Sweden, the National Food Agency of Sweden and the Swedish University of Agricultural Sciences.
The findings have been published in the Annals of Applied Statistics:
Ranta, J., Lindqvist, R., Hansson, I., Tuominen, P., Nauta, M.
A Bayesian approach to the evaluation of risk-based microbiological criteria for Campylobacter in broiler meat. Annals of Applied Statistics 2015, Vol. 9, No. 3, pp. 1415 - 1432.
For further information, please contact:
Jukka Ranta, Senior Researcher, PhD, Risk Assessment Research Unit,
tel. +358 (0) 40 489 3374