Helping companies validate their microbiological methods
Campden BRI case study
Analytical microbiologists are continuously searching for faster methods for detecting, identifying and counting problem micro-organisms - and new approaches are being developed all the time. In order to use these alternative methods, however, a laboratory must be confident that the results they obtain are as reliable as those obtained using the standard methods.
Such assurance usually comes in the form of method validation against an international standard (e.g. ISO16140) through a recognised body such as the Association of Official Analytical Chemists (AOAC) and MicroVal. In these trials the method is independently evaluated to test its performance with a range of product types. We have provided independent evaluation services for several companies. One such company is Hyserve.
Dr Stephan Speidel of Hyserve comments:
"We have worked with Campden BRI over the past ten years to achieve MicroVal and AOAC validation for a number of our dehydrated media formats. Their practical microbiological knowledge from a food industry standpoint, combined with their understanding of microbiological methods and validation in general, means that they are the obvious partner of choice for helping us get our methods approved.
Our "Compact Dry" methods are ready–to–use dry media sheets comprising culture medium and a cold–soluble gelling agent, rehydrated by inoculating 1ml diluted sample into the centre of the self–diffusible medium. Validated methods are now available for a range of organisms including Total Viable Count (TVC), Escherichia coli, Enterobacteriaceae, coliforms and Staphylococcus aureus. The tests are easy to perform and require little incubation space. The colonies are easy to read due to the good differentiation achieved by the chromogenic and other dye systems that we use.
In Compact Dry TC (TVC) , metabolizing bacteria form red colonies due to the redox indicator tetrazolium salt, whilst in Compact Dry CF (coliforms) Coliforms form blue/blue green colonies due to the chromogenic substrate X–Ga. Food residues are easy to distinguish, because they do not change the colour."