The effects of the type and thickness of plastic coating on the migration of off‐odours and off‐flavours from fibreboard materials to certain model foodstuffs were studied in microwave oven heating. Correlations between sensory, physical and chemical properties of fibreboard materials were also determined. The plastic coating served as a very good barrier to the transfer of off‐flavours into foodstuffs. Polyester coating prevented the migration of off‐flavours, whereas polyethylene and polypropylene were effective only in certain cases. With the last two plastics, the thickness of the coating layer also affected the amount of off‐flavours migrating. Generally, the sensory properties of the materials did not correlate with either the melting behaviour of the plastic coating or the amount of volatile compounds generated.