Development of an Integrated Procedure for the Detection of Central Nervous Tissue in Meat Products Using Cholesterol and Neuron-Specific Enolase as Markers

Abstract

The emergence of a new variant of Creutzfeldt-Jakob disease during the bovine spongiform encephalopathy epidemic has focused attention on the use of tissue from the central nervous system (CNS) in food. So far, the banning of CNS tissue could not be effectively controlled because procedures for detection were missing. With regard to preventive health protection and labeling law enforcement, we have developed an integrated procedure for the detection of CNS tissue in meat products. Herein, we show that antigenic characteristics of neuron-specific enolase (NSE) quantitatively survive technological treatment including severe homogenization and pressure heating. Using both poly- and monoclonal antibodies against NSE in the Western blot, bovine and porcine brain could be detected in sausages, albeit with varying sensitivity (1 to 4%). Sensitivity was increased after reduction of fat content (30 to 40%) of the samples by means of a soxhlet extraction. This made possible the detection of brain addition as low as 0.25% when using monoclonal antibodies. Immunohistology showed distribution of CNS tissue in heat-treated meat products to be homogeneous. Immunoreaction was not found to be bound to morphologically intact histological or cytological structures; however, it proved to be highly specific. The quantification of cholesterol provides a low-cost screening method for the rapid identification of meat products, suspicious with regard to CNS tissue addition. Cholesterol content increased by 26 mg per 100 g of fresh substance for each percentage of brain added to internally produced reference material. Using three different approaches (internal reference material, raw material, and field samples), a provisional cutoff point of normal cholesterol content was calculated for emulsion-type cooked sausages to be 115 mg/100 g (P < 0.05).