Unusual Flavor Defect in Cheese Similar to the Odor of Feline Urine (Felis libyca domestica)

A sporadically occurring flavor defect in Cheddar cheese is characterized by an odor of feline urine. Gas chromatography and mass spectrometry revealed a sixcarbon numounsaturated ketone in vacuum distillates of fat from affected portions of cheese. This ketone was absent or present in much lower concentrations in unaffected portions of the same cheese. The odors and gas chromatograms of fractions of distillates obtained by vacuum sublimation indicate that the ketone did not have a feline odor, the unidentified feline substance subliming at a slightly higher temperature.