Modelling salmonella growth to produce safer pork
28th April 2011
Salmonella infections are among the most common bacterial causes of food-borne gastroenteritis in humans, with a number of different potential sources including meat, eggs, and fresh produce. In the EU, up to 20% of human salmonellosis cases are thought to be due to consumption of contaminated pork products. Most EU countries have established programmes to control it and there is an ongoing EU baseline study. An EU funded research programme, called BIOTRACER, is investigating the main sources of contamination and to help in this the IFR has led the development of a tool for modelling and predicting the growth of Salmonella in the pork supply chain.
Tracing the cause of bacterial contamination to a particular stage of the supply chain can be difficult because of uncertainty surrounding how the bacteria grow at the different stages and under different environmental conditions. Carmen Pin and colleagues at IFR, in Italy and in Greece have sought to bring more certainty into the inference by breaking down the process systematically, to produce a model for how Salmonella growth can be affected at each production step.
Temperature, pH and water activity fluctuate between different stages in processing of pork, and these conditions affect the growth and survival of Salmonella. Data on Salmonella growth in different conditions have been produced by numerous research groups around the world, and brought together in databases such as Combase.
The ComBase database is a web-based collection of measurements describing how microbes respond to different environmental factors. Combase is a collaboration between IFR, the US Department of Agriculture Research Service and Australia’s Food Safety Centre, and is a central, open-access repository for quantitative microbiological data. The researchers found over 700 records in the Combase database describing the growth of Salmonella in a wide range of different conditions relevant to the pork supply chain.
Different models were then combined to give predictions on the concentrations of Salmonella at the different stages of the pork supply chain, under varying temperature, water activity and pH conditions. These predictions were validated in several pork products.
The models are freely available online via a user-friendly computing tool at [link no longer available] to allow users to enter their own conditions and get an estimate of the Salmonella concentrations at any stage of the process. This allows a better understanding of which steps are most critical in the pork supply chain and assists the overall control of Salmonella and the production of safe food.
This research was supported by the European Union-funded Integrated Project BIOTRACER (contract #036272) under the 6th RTD Framework, and involved researchers from IFR, Istituto Zooprofilattico Sperimentale della Lombardia e dell’Emilia Romagna and the Agricultural University of Athens. It was published in the International Journal of Food Microbiology in March 2011.
Modelling Salmonella concentration throughout the pork supply chain by considering growth and survival in fluctuating conditions of temperature, pH and aw Carmen Pin et al, International Journal of Food Microbiology 145 S96–S102 doi:10.1016/j.ijfoodmicro.2010.09.025