Inter-laboratory validation of a reference method for the determination of boar taint compounds by GC-MS and LC-MSMS

Abstract

Meat from male pigs may develop an off-flavour, commonly known as boar taint. For that reason male piglets are surgically castrated at young age to avoid the potential off-flavour formation. Animal welfare concerns have triggered research into alternatives to surgical castration of male piglets with the long-term goal of abandoning it by 1 January 2018. The ALCASDE study has shown that the agreement of testing results for androstenone and skatole in pig fat produced in several laboratories was not satisfactory and one of the conclusions of this project was that in a follow-on project a standardised reference method should be elaborated to rectify this shortcoming. In the suggested reference method, the 3 marker compounds (skatole, androstenone and indole), for boar taint are quantified in pork fat by isotope dilution gas chromatography mass spectrometry (GC-MS) isotope dilution liquid chromatography tandem mass spectrometry (LC-MSMS). The fat is separated from the ground pork fat tissue sample via melting and centrifugation thereafter. The fat is spiked with isotopically labelled standards and prepared for size exclusion chromatography (SEC). The SEC purified sample is evaporated nearly to dryness and after addition of an injection standard analysed by GC-MS in single ion monitoring mode or by LC-MSMS in selected reaction monitoring mode. This method has been validated to obtain the method performance characteristics. The within laboratory precision (repeatability relative standard deviation, RSDr) ranges from about three per cent to about ten per cent and the reproducibility relative standard deviation (RSDR) between 10 % and about 30 %. The level of 30 % was exceeded only for one analyte/sample combination. The method has proven to be robust and free from matrix interferences. The method is sensitive enough to determine the off-flavour compounds at the sensory threshold values with acceptable analytical precision. When summarising the method performance characteristics and comparing them to requirements for official food control methods in the area of food contaminants it can be concluded that the method is fit for its intended purpose.