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Validation of Western blot methods to monitor the presence of added bovine and porcine blood proteins in meat products - FA0122

Since 2003 the definition of meat for labelling purposes is restricted to skeletal muscle with naturally adherent fat and connective tissue. It is alleged, however, that blood proteins in the form of plasma or serum from bovine and porcine sources are added to processed meat products (for example, meat emulsions such as hot dogs and sausages, and burgers) to extend the protein content and increase the water holding capacity of the product. This in turn reduces production costs and, unless noted on the label, constitutes fraud.

The addition of extra protein of blood origin is difficult to detect, and current tests do not distinguish between meat and blood proteins. There is a need therefore for alternative methods to detect the presence of additional bovine and porcine blood proteins in processed meat products.

In a previous project (Q01092) commissioned by the Food Standards Agency, the Nottingham Trent University group produced highly specific antibody reagents that react with (detect) a specific protein in beef and pork blood. These reagents can be incorporated into sensitive tests (‘immunoassays’) which can monitor the levels of the proteins (and therefore the levels of blood) in processed meat products. Since meat contains residual blood, the fraudulent addition of blood is detected by estimating how much extra blood is present in the product, above what is naturally present. For the tests to be most useful for laboratories who are authorised to analyse food samples (eg Public Analyst laboratories) it is important to establish the range of blood levels normally found in meat; and this is the first aim of the project. Once this range is established for pork and beef meat the information can then be incorporated into the procedures used by these laboratories.

Although there is some evidence that meat products being sold in the market place contain non-declared additional blood, it is not known how big the problem is. Before commercial samples can be surveyed it is important to ensure that the tests (the immunoassays) are accurate. Therefore the second aim of the project is to establish how accurate the tests are in estimating additional blood in meat samples which have been spiked with blood in the laboratory.
The initial aim of the project is to validate the use of Western blot methods to monitor the presence of added bovine and porcine blood proteins in meat products. In order to achieve this aim the following objectives have been identified:

1. Determination of threshold levels of residual serum in meat ( 6 months, working 3days/week)
This will involve (a) analysis of residual serum in different cuts of pork and beef, and (b) checking that these levels are representative of residual serum found in pork and beef mince. This information is needed for inclusion in the SOP (Standard Operating Procedure for immunoblot analysis of bovine or porcine serum in extracts of processed meat products), to help PAs or other users interpret the results.

2. Establishing precision of Western blotting assays to determine addition of porcine/bovine serum to pork/beef (5 months, working 3days/week).
This information is needed to ensure the robustness of the method in advance of any survey.

3. Production of final report of objectives 1 and 2 and updating SOP (1 month, working 3days/week)

Once the above objectives have been successfully achieved, other objectives will be explored following consultation with Defra:

4. Pilot use of Western blot methods to survey added serum in meat products (approx. 4 months, working 4 days/week)
This will involve screen of 100 survey samples (to be discussed with Defra) for the presence of added pork serum or added bovine serum.
5. Production of final report of objective 4 (approx. 1 month, working 4days/week)
Project Documents
• FRP - Final Report : Further validation of assays to monitor offal and added serum in meat products using commercial samples   (1881k)
• ANX - Annex : Appendices FA0122   (964k)
• TRP - Technical Report : Standard Operating Procedure (SOP)   (281k)
Time-Scale and Cost
From: 2012

To: 2014

Cost: £156,890
Contractor / Funded Organisations
Nottingham Trent University