pubs.acs.org/JAFC Published on Web 01/04/2011 © 2011 American Chemical Society J. Agric. Food Chem. 2011, 59, 953–959 953 DOI:10.1021/jf1038212 Evolution and Occurrence of 1,8-Cineole (Eucalyptol) in Australian Wine DIMITRA L. CAPONE,* ,†,‡ KATRYNA VAN LEEUWEN, † DENNIS K. TAYLOR, ‡ DAVID W. JEFFERY, †,§ KEVIN H. PARDON, † GORDON M. ELSEY, †,§ AND MARK A. SEFTON †,§ † The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, South Australia 5064, Australia, and ‡ School of Agriculture, Food and Wine, Waite Campus, The University of Adelaide, PMB 1, Glen Osmond, South Australia, 5064, Australia. § Present address: The University of Adelaide. A new method has been developed for the quantitation of 1,8-cineole in red and white wines using headspace solid-phase microextraction (SPME) combined with stable isotope dilution analysis (SIDA) and gas chromatography-mass spectrometry (GC-MS). An extensive survey of Australian wines (44 white and 146 red) highlighted that only red wines contained significant amounts of 1,8- cineole (up to 20 μg/L). Hydrolytic studies with limonene and R-terpineol, putative precursors to 1,8- cineole, showed a very low conversion into 1,8-cineole (<0.6%) over a 2 year period, which does not account for the difference between white and red wines. 1,8-Cineole was chemically stable in model wine solution over 2 years, and absorption from a Shiraz wine by bottle closures was most evident for a synthetic closure only (14% absorption after 1 year). Two commercial ferments at two different locations were monitored daily to investigate the evolution of 1,8-cineole throughout fermentation. Both ferments showed daily increases in 1,8-cineole concentration while in contact with grape solids, but this accumulation ceased immediately after pressing. This observation is consistent with the extraction of 1,8-cineole into the ferment from the solid portions of the grape berries. KEYWORDS: Wine aroma; 1,8-cineole; eucalyptol; SPME; SIDA; GC-MS INTRODUCTION 1,8-Cineole, correctly identified by Jahns in 1884 ( 1 ), was initially recognized as the major constituent of the essential oil from leaves of Eucalyptus globulus by Cloe¨z, who labeled it eucalyptol ( 2 ). Eucalyptus essential oil (containing up to 90% 1,8-cineole) has since been used at low concentrations as a flavoring agent in a diverse range of foods and beverages ( 3 , 4 ), as a constituent in fragrances, cosmetics, and aromatherapy ( 3 ), and as a therapeutic ingredient with a range of applications (see refs 5 -7 and citations therein). In fact, the medicinal use of eucalyptus leaves by indigenous Australians dates back many millennia ( 7 ). 1,8-Cineole is generally recognized as safe (GRAS) and has been used as an additive in cigarettes (see ref 8 and citations therein), evidently to improve flavor properties, reduce throat irritation, or enhance the cooling effects of menthol. 1,8-Cineole has a characteristic aroma described as “eucalyp- tus”, “fresh”, “cool”, “medicinal”, and “camphoraceous” and was first reported in wine by Herve et al. ( 9 ). That study showed that 1,8-cineole played an important role in the occurrence of “eucalyptus” character in wine. They also determined the differ- ence and recognition thresholds of 1,8-cineole in a California Merlot as 1.1 μg/L and 3.2 μg/L, respectively ( 9 ). Herve et al. proposed that the “eucalyptus” character in wines occurs due to vineyards being in the vicinity of eucalyptus trees ( 9 ), but the origin of 1,8-cineole in wine is still unclear. To explain the presence of 1,8-cineole in Tannat grapes and wines from Uruguay, Farina et al. suggested that terpene com- pounds such as R-terpineol and limonene were possible precur- sors ( 10 ). Their postulated pathway to the formation of 1,8- cineole involved the hydration of limonene, forming R-terpineol, which was further hydrated to give a mixture of 1,8-terpines, with cyclization of trans-1,8-terpine leading to 1,8-cineole. They also put forward other theories involving double-bond epoxidation to explain the formation of minor components arising under their experimental conditions ( 10 ). Their studies with model wine showed that 1,8-cineole can be produced from limonene and R- terpineol under accelerated aging conditions at wine pH, but they gave only semiquantitative data for the products. Moreover, they found that 1,8-cineole concentrations in their Tannat grape samples at the beginning of ripening were very low, but showed a significant increase throughout ripening, and they determined an odor threshold for 1,8-cineole in the Tannat wine similar to that reported for Merlot ( 10 ). Further confounding matters, the results from Farina et al. contrast with the work of Kalua and Boss, who found that 1,8- cineole levels decrease during ripening of Australian Cabernet Sauvignon and Riesling grapes ( 11 ), whereas other Tannat wines from Uruguay were shown to contain terpenoids but not 1,8- cineole ( 12 ). It is interesting to note that both Tannat studies involved vineyards in southern Uruguay, which also happens to be an area where eucalyptus plantations are readily encoun- tered ( 13 ). Nonetheless, the studies relating to 1,8-cineole indi- cated there are a number of possible explanations for its presence *Corresponding author (phone þ61 8 8303 6600; fax þ61 8 8303 6601; e-mail dimitra.capone@awri.com.au).