Pathatrix Pathogen Testing System, United Kingdom

Cadbury is one of the best-known chocolate-producing companies in the UK and Europe. In 2008, the company introduced a new food safety testing system across its facilities.

This was in response to some production problems in January 2006 at the Cadbury facility in Marlbrook, Herefordshire, UK, after a leaking pipe in the process contaminated the chocolate crumb.

This resulted in product recalls costing £50m for seven large and small bar milk chocolate products that could potentially have been contaminated with Salmonella (Montevideo strain).

Cadbury has now introduced the new Pathatrix Pathogen testing system, alongside some others, to increase its food safety standards.

The improvements have cost the company £20m to date. Other large food companies such as Con Agra Inc in the US have also adopted the technology across several plants.

PATHATRIX

The developer of the Pathatrix system is Matrix Microscience of Newmarket, UK. Cadbury decided to adopt the system because it could handle the analysis of a large number of samples at once and process them in around 30 minutes, with final results obtained in five to 21 hours.

The system integrates well with other technologies and provides a high-quality and practical asset for the company's laboratories.

THE SYSTEM

The system is a microbial detection system based upon small magnetic particles that are coated with antibodies specific to the pathogen to be detected in the product. The system consists of a work station and also a consumable tube (containing the magnetic antibody particles) which are used to process the sample.

The food sample is pumped through the tube for 30 minutes where the immobile paramagnetic antibody particles on the tube walls capture/bind the specific bacteria from the complex food matrix (liquid chocolate). The capture phase recirculates the sample, which can be as large as 250ml; the sample passes over the phase twice every minute. If the system is heated then bacteria can be cultured at the same time to enhance the detection limits/sensitivity.

Following the strictly controlled capture phase (time and temperature), the sample can be analysed using a variety of methods including: plating and incubation; COLORTRIX; FLURATRIX (fluorescence microscopy); serology; PCR (polymerase chain reaction); ELISA (Enzyme-Linked ImmunoSorbent Assay); and/or DNA probe.

The food matrix is washed from the captured bacteria and these can then be eluted and prepared in solution for culture or subsequent analysis. The magnet is removed and the bead/bacteria complexes are washed off the capture phase, collected and concentrated in a wash tube.

The Pathatrix system is validated for Salmonella, E.sakazakii, MAP, Listeria, Campylobacter and E-coli O157. Detection limits are around 1–10cfu (colony forming units) per 25g sample.

POOLING SYSTEM

The system can also be configured to save time by using a pooling system to analyse five sub-samples for pathogens simultaneously. Five 50ml samples are pooled together in a composite sample using post-enrichment methodology and the sample run as one. If there are any positives then the sub samples are fully traceable back to the original samples, which can then be rerun for further elucidation.

This method saves time (60%), labour and money where a larger number of samples will be taken from any one process. Pooling is a recognised technique as the majority of samples in any food process (98%) will provide a negative result. If a positive is obtained the culprit is then one of only five.