By Joy Gaze - 9 March 2015

The Microbiology research group that I manage (Heat Resistance and Decontamination) has a long history of expertise in establishing process lethality. Over the years we have devised techniques suitable for demonstrating the microbiological safety of a wide range of process technologies. We have been most fortunate to have had the opportunity to expand our facilities to include a process hall dedicated to microbiological studies.

This addition allows us to incorporate pathogens directly into our studies and provide data on the lethal effect of a range of process technologies.

We have used a number of different inoculation techniques, all designed to ensure that the microorganisms are exposed to the actual treatment. The data obtained allows processes to be validated and we use our expertise to interpret the adequacy and subsequent safety of the different treatment regimes under consideration. Typically for pasteurised products, the target pathogen would be expected to be reduced by the treatment by 6 logs in order to render the food product safe. Alternatively if the treatment is considered to be a sterilisation process then greater log reductions would be considered necessary.

The experimentation would be controlled with a set concentration of the pathogen being introduced, the process applied as normal and then the surviving organisms recovered to allow the actual log reduction to be calculated. The ability of organisms to survive can be influenced by the moisture availability, temperatures achieved, composition of the food material, and if any rehydration or dehydration occurs during the treatment, or if the microorganisms are protected by the food components or encapsulated in oil. Consequently each validation is unique and has its own set of parameters that have to be considered in order to demonstrate the required lethality.

Recent installations and experimentation have combined the skills from several departments at Campden BRI and studies have been conducted using process technologies including the following: coffee roasting, steam autoclaving, moist heating over the temperature range 50 to 140°C, dry heating, Ohmic heating and High Pressure processing. In each case the lethality of the treatments has been assessed in relation to the target organism and the number of log reductions determined. These types of studies can also be designed to determine process optimisation by evaluating the lethality of a matrix of combined processing conditions in order to find the best combination. Our client base is global with work conducted for many countries across the world.

In the Microbiology Process Hall we have also conducted vegetable washing decontamination studies, the evaluation of cold plasma technology, the effectiveness of ozone treatments and numerous other chemical decontamination solutions. We have a test rig installation which is used to evaluate pumps, valves and various other manufacturing kit to EHEDG standards for 'clean in place' approval. In relation to catering we have also evaluated the adequacy of cooking/reheating instructions; some of our studies have been conducted in ovens, some using frying, grilling and many other forms of pasteurisation including blanching.

Many of the above research studies are conducted on a confidential basis for clients as a service, if you have an interest in using this service please contact us.