Food Branch

Challenge Testing

Challenge testing is designed to provide behavioral information on microorganisms artificially introduced into food and stored under foreseeable transport, distribution and storage conditions, and reflect their intended shelf life. In our laboratory we perform a microbiological challenge testing to evaluate the growth potential (δ). The purpose of the study is to demonstrate that ready-to-eat foods meet the food safety criteria specified for the selected microorganism throughout their shelf life. Our analysis are directed to ready-to-eat food manufacturers to take steps to control the contamination by microorganisms and the growth of pathogens in the product by the end of shelf life.


Challenge testing is carried out in accordance with the EURL LM TECHNICAL GUIDANCE DOCUMENT for conducting shelf life studies on Listeria monocytogenes in ready-to-eat foods (version June 3-6, 2014) and standard NF V 01-009 Food traceability and safety – Management and hygiene – Guidance for performing microbiological growth tests (May 2, 2014).


We use technology at each stage of our research by developing a challenge test for specific products and microorganisms in the range of production schedules and manufacturing conditions. Knowledge of product pH, water activity, temperature and storage time, added preservatives, and the presence of starter cultures helps in the proper design of the study. Challenge test results are used to qualify products as ready-to-eat foods, where the growth of the test organism may be present, or as ready-to-eat foods in which the growth of the test organism does not occur during its shelf life. If the initial contamination level is known, the microbial growth potential enables to estimate the final concentration for identical food, strain, and storage conditions. The growth potential can also be used to calculate the initial number of colony forming units in food that will allow complying with the set limit at the end of shelf life.