Performance comparison of two analytical methods for the detection of tissues of the central nervous system in sausages:: results of an interlaboratory study

An international collaborative trial has been conducted to evaluate two methods for the detection of tissues of the central nervous system (CNS) in meat products (sausages). The two methods are commercially available as test kits both based on immunochemistry. The methods differ in the type of marker and methodology applied. One uses western blotting in order to detect neuron specific enolase (NSE) as a marker, while the other is based on the detection of glial fibrillary acidic protein (GFAP) by applying an enzyme linked immunosorbent assay (ELISA). Twenty-one laboratories from nine European Countries participated in the intercomparison study. As one laboratory reported consistently too low results, revealing problems in executing the method descriptions, its results were excluded from further statistical evaluation. When comparing the performance of both methods obtained in this validation, it was revealed that both methods performed well with a detection limit of at least 0.5% CNS in those test materials that contained non-heat-treated and medium heat-treated brain (sausages cooked at 80 degreesC). Regarding the strongly heat-treated brain (sausages cooked at 120 degreesC) the detection limit was determined to be 0.5% CNS for the GFAP test kit, however 2% CNS for the NSE test kit.