Analysis of Free and Bound Aroma Compounds in Grape Berries Using Headspace Solid-Phase Microextraction with GC-MS and a Preliminary Study of Solid-Phase Extraction with LC-MS

Helena Prosen,a* Lucija Janeš,a Matija Strlič,a Denis Rusjan,b Drago Kočara

aUniversity of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5 SI-1000 Ljubljana, Slovenia.
Tel.: +38612419176,
Fax: +38612419220,
bUniversity of Ljubljana, Biotechnical Faculty, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia

Paper based on a presentation at the 12th International Symposium on Separation Sciences, Lipica, Slovenia,
September 27–29, 2006.

An extraction procedure for the aroma compounds from musts and wines has been developed, using solid-phase microextraction(DVB/CAR/PDMS fibre) from the headspace of heated samples (50 °C). Analysis was performed withgas chromatography – mass spectrometry. The method was applicable to the analysis of different aroma compounds(aliphatic, aromatic aldehydes, terpenes) in a broad concentration range (1–5000 µg L–1). A stir-bar sorptive extractionprocedure was also tested, but was not effective enough due to the lack of a suitable desorption device. Free aroma compoundsin must samples of different grape varieties were analysed, and their release was evaluated after enzymatic oracidic hydrolysis. Different hydrolytic approaches were tested and the most successful was the enzymatic hydrolysis(with two different enzymes) and acidic hydrolysis at pH 3. Acidic hydrolysis at pH 1 resulted in substantial decompositionand re-arrangement reactions of terpenes. Non-hydrolysed terpene glycosides were extracted from the musts usingsolid-phase extraction and the extract was analysed with liquid chromatography – mass spectrometry (electrosprayinterface). Some compounds were tentatively identified as terpene glycosides.

Keywords: food aroma, grape, wine, extraction, chromatography, mass spectrometry,