Sous vide cooking involves vacuum-packing food in a plastic pouch and heating it in a water bath, allowing for precise temperature control to create new textures and flavors. IFR has been researching the technique for the Food Standards Agency to find out if food poisoning bacteria can grow and survive at these lower temperatures.
Most data available on microbial food growth is based on temperatures below 40 degrees Celcius (104 degrees Fahrenheit), which focuses on how bacteria grow in food storage conditions, or above 60 degrees Celcius (140 degrees Fahrenheit), when bacteria is usually killed. However, many sous vide foods are cooked at temperatures between 42 degrees and 70 degrees Celcius (107.6 degrees to 158 degrees Fahrenheit), so a lack of information on foods cooked in this range makes it difficult to gauge the safety of low-temperature heat treatments.
Data available through ComBase, a database for predictive microbiology, offers extensive information on microbial growth, but it still needs upgrading to understand the hazards of E. coli, Salmonella and Listeria monocytogenes between 40 and 60 degrees Celcius. Sandra Stringer and her colleagues at IFR gathered information to assess the hazards associated with lower temperature cooking, and they also carried out a feasibility study on extending models in the Combase database. This will help ensure that the safety assessment for sous vide foods is consistent and effective.