To investigate the possible presence of protein‐bound mutagens in food an analytical procedure has been devised in which the sample is enzymically hydrolysed, fractionated by HPLC and examined by a modified liquid incubation Ames assay. To validate the method MeIQx was added, as a model compound, to beefburger and a recovery of 82% obtained. The limit of detection for protein‐bound mutagens was 1 μg/kg, expressed as equivalents of MeIQx. No detectable mutagenicity was observed when the procedure was applied to samples of well cooked beefburger, irradiated chicken or mycoprotein.