Research – Finland – Risk assessment of STEC in medium-cooked ground beef patties

Ruokavirasto

Abstract
Medium-rare or medium-done ground beef patties are associated with the risk of
microbiological contamination, especially from Shiga toxin-producing Escherichia coli
(STEC) bacteria, which can cause gastrointestinal infections. The objective of this risk
assessment was to evaluate the food poisoning risk associated with medium-done
ground beef patties made from Finnish beef and served in foodservice establishments.
Simultaneously, the Finnish Food Authority’s recommendation for preparing medium
ground beef patties was assessed. The recommendation includes, among other things, the
removal of surfaces from the meat before grinding it into ground beef in the kitchen of food
service establishments.
The risk assessment used an application based on a Bayesian statistical model. The data
included information collected from the Finnish Food Authority’s registers and a survey
conducted as part of the project for foodservice establishments. To evaluate the Finnish
Food Authority’s recommendation, a study was conducted to determine how STEC bacteria
are transferred from the surface of experimentally contaminated roast beef to the inner
parts of the meat when the surfaces are removed.
The risk of the population getting sick was greatly influenced by the proportion of ground
beef patties served medium and how hot the patties were heated. In a situation where
approximately a tenth of the patties were cooked medium (internal temperature 55°C),
there would be 100 illnesses per 100,000 residents in Finland per year. Surface removal as a
risk management measure only worked in those experiments with roasts when the level of
contamination was low. Even then, some of the tested roasts still had STEC bacteria.