Trace-level determination of polar flavour compounds in butter by solid-phase extraction and gas chromatography-mass spectrometry

Volatile compounds are responsible for the aromas of butter. A simple techn ique for the determination of these components is described which is based on solid-phase extraction (SPE) after melting of the butter and separation of the aqueous phase from the fat. Volatile flavours present in the water f raction are collected by off-line SPE on cartridges packed with a copolymer sorbent. After desorption with 500 mu l of methyl acetate, 1-mu l aliquots are quantified and/or identified by gas chromatography-mass spectrometry. The procedure was tested with respect to recovery, linearity and limit of d etection in real-life samples using five polar model analytes. It allows th e characterisation of polar flavour compounds in butter prior to and after heat treatment at 170 degrees C. From the five model compounds, vanillin, t races of diacetyl and maltol were found to be present in the butter samples . After heat treatment 500-1000-fold increased concentration of maltol, and substantial amounts of furaneol were detected. (C) 1999 Elsevier Science B .V. All rights reserved.