The Institute of Food Research (IFR) has conducted a research for the UK Food Standards Agency (FSA) to establish if the cooking technique sous vide is safe.
Sous vide uses lower temperatures to improve food quality. This technique could be a step closer to being more widely adopted after the IFR scientists evaluated the steps needed to ensure the process is safe.
For the study, Dr Sandra Stringer and colleagues at the IFR have gathered the information needed to properly assess the hazards associated with lower temperature cooking.
Sous vide cooking involves vacuum packing food in a plastic pouch and then heating in a water bath. This cooking involves precise nature of the temperature control, allowing innovative use of the technology to create new textures and flavours by manipulating the behaviour of food components such as proteins, starches and fats.
As microbial safety is important in designing new recipes and processes, data has been collected on how well food poisoning bacteria grow and survive in different foods at different temperatures. This data has been collected together and made available through ComBase, a BBSRC-supported National Capability based at IFR. Food manufacturers and academics regularly consult ComBase's extensive database of microbial growth information.
Recently, there has been an increase in the number of sous vide foods being cooked at lower temperatures, e.g. 42°C to 70°C. Most data on microbial growth in food is based on temperatures below 40°C. Other studies have looked at the temperatures at which bacteria are killed, usually around 55-60°C and above.
However, there is a lack of information in the range of about 40 to 60°C. This makes it very difficult for cooks, manufacturers, regulators and enforcement officers such to calculate the lethality of such low temperature heat treatments and judge the risk of foods containing pathogens.
For the study, the scientists also conducted a feasibility study on extending models in the 'Combase Predictor' database. Specifically they investigated how much work would be needed to upgrade the ComBase database to model the hazards E. coli, Salmonella and L. monocytogenes between around 40 and 60°C. This would help ensure that the safety assessment for sous vide foods is consistent, effective and commensurate with any risk to public health.
This work was carried out as part of a project for the Food Standards Agency (FSA) to provide the best information on this issue and propose a way forward to fill the knowledge gap.