Identification of central nervous system tissue in retail meat products.

A procedure to detect tissues from the central nervous system that involved quantification of cholesterol and immunochemical detection of neuron-specific enolase and glial fibrillary acidic protein was used to analyze 402 samples of heat-treated meat products from various food outlets in Germany. The cholesterol content of 16 samples (4.0%) indicated the possible presence of central nervous system tissue because the levels exceeded the normal maximum cholesterol content of cooked sausages. In 7 of these 16 heat-treated meat products, immunoblotting of both neuron-specific enolase and glial fibrillary acidic protein confirmed the presence of CNS tissue. Repeated sampling by veterinary officials and analysis by both cholesterol quantification and immunoblotting confirmed these findings. Whereas all of the control samples (with and without added central nervous system tissue) were correctly classified by both cholesterol quantification and immunoblotting, negative results of immunoblotting must be carefully interpreted in the case of intensively heat-treated meat products. Thus, studies have yet to establish an increase in sensitivity of immunoblotting of neuron-specific enolase and glial fibrillary acidic protein. However, the detection of illegal use of central nervous system tissue in heat-treated retail meat products demonstrates the need for suitable analytical methods to control transmissible encephalopathies and to enforce labeling laws.