Cause of catty odour formation in packaged food

In two different ‘cook‐in‐the‐bag’ ham products packed in polyamide‐ethylene ionomer laminate pouches, the same obtrusive catty off‐odour was complained about. In this paper the analytical resolution of a complex off‐odour problem is described. Identification of the catty odour as the mesityf oxide‐hydrogen sulphide adduct 4‐methyl‐4‐mercaptopentan‐2‐one is followed by investigating the formation of the off‐odour with the aid of different model experiments. It is pointed out that the ethylene ionomer material that is used for the sealing layer of the multilayer packaging film has some dehydration property for diacetone alcohol, which was found as a residual solvent in the film material in question. Probably this pathway seems most likely to be responsible for the off‐odour.