Investigating the coffee flavour in South African Pinotage wine using novel offline olfactometry and comprehensive gas chromatography with time of flight mass spectrometry

Author(s): Yvette Naudé, Egmont R. Rohwer
Department of Chemistry, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa

Published By: Journal of Chromatography A

Issue: 1271

Year of Publication: 2013


Abstract: Pinotage wine from several South African wine cellars has been produced with a novel coffee flavour. We have investigated this innovative coffee effect using in house developed solventless sampling and fractionating olfactometric techniques, which are unique in their ability to study synergistic aroma effects as opposed to traditional gas chromatography olfactometry (GC-O) which is designed to, ideally, evaluate single eluting compounds in a chromatographic sequence. Sections of the chromatogram, multiple or single peaks, were recaptured on multichannel open tubular silicone rubber (polydimethylsiloxane (PDMS)) traps at the end of a GC column. The recaptured fractions were released in a controlled manner for offline olfactory evaluation, and for qualitative analysis using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC×GC–TOFMS) for compound separation and identification, thus permitting correlation of odour with specific compounds. A combination of furfural and 2-furanmethanol was responsible for a roast coffee bean-like odour in coffee style Pinotage wines. This coffee perception is the result of a synergistic effect in which no individual compound was responsible for the characteristic aroma.

 Acknowledgment(s):We wish to thank Gerhard Overbeek for assisting in the extraction of wine and aroma evaluation, Phakama Botha for assistance in wine extraction, Dr Fanie van der Walt for the custom-built olfactometer, David Masemula for the assembly of multichannel PDMS traps, Dr Peter Gorst-Allman from LECO Africa (Pty) Ltd. for use of a LECO Pegasus 4D GC×GC–TOFMS, Philip Langenhoven from LECO Africa (Pty) Ltd. for sponsorship, Jack Cochran from Restek for kind donation of GC columns and consumables, SASOL and the National Research Foundation (NRF) for financial support.