UK Horse Meat in Beef Tests Sound and Reliable21 September 2014
Following the horse meat scandal in the UK in 2013 a series of tests were carried out on samples of meat and food products to ensure that the food and ready meals on the shelves in the supermarkets met the required standards.
The sampling and testing was carried out after the Department for Food and Rural Affairs (Defra) and the Food Standards Agency (FSA) commissioned a UK Survey of the beef products as part of a co-ordinated response to the EU horse-meat issue.
Samples were taken on a formal basis, allowing UK Public Analysts to choose which methods to apply.
A range of analytical methods were available for detection of horse DNA, but the respective Limits of Detection (LOD) were often different, not robustly defined, or expressed using different measurement units.
The LOD of methods used in the UK Survey needed to be robustly tested and qualified so that results obtained from the samples could be interpreted with confidence.
To achieve this a study, Method Verification of the LOD Associated with PCR Approaches for the Detection of Horse Meat, was carried out by Eloise Busbya and Malcolm Burns from LCG in Teddington.
The aim of the study was to evaluate the LOD of three selected methods used by Public Analysts as part of the UK horse-meat Survey in terms of uniform w/w (raw horse-meat in a raw beef (meat) background) sample measurements.
The three methods evaluated were a PCR-Capillary Electrophoresis approach (PCR-CE as described in Defra project FA0220, LOD reported as approx 1 per cent w/w); PrimerDesign (LOD of approx. <100 mitochondrial copies); and Neogen BioKits (LOD approx 0.1 per cent w/w).
A range of gravimetrically prepared raw horse-meat in raw beef meat (w/w) materials were produced as part of the current study and authenticated for species identity.
These materials were used to challenge the three methods in order to estimate the LOD in terms of w/w (meat to meat) based on internationally accepted guidelines and best measurement practice for LOD and PCR methods.
Estimates for the LOD were based upon 60-115 replicates of the 0.1 per cent w/w material, depending upon the method evaluated. More than 250 replicates of the 0.1 per cent w/w material were assessed across the three analytical methods, representing five independent DNA extractions.
The results have shown that the three approaches of the PCR-CE/FA0220 method, the Neogen BioKits method5, and the PrimerDesign method all have the potential and capability of reaching a limit of detection (LOD) of less than 0.1 per cent w/w raw horse meat in a raw beef (meat) background, if Quality Procedures and Good Laboratory Practice for molecular biology methods were adhered to.
This helped afford good comparability of results for these three methods, and in turn contributed to ensuring that the results from the UK Survey of beef products in 2013 were interpreted with confidence.
The researchers said that Defra and the FSA could therefore have confidence in the approximate levels of sensitivity of these three methods as applied as part of the UK Horse Meat Survey exercise, and therefore have assurance that the probability of detecting the horse DNA target was approximately the same between the three methods.
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