Flavor Chemistry of Wine and Other Alcoholic Beverages

Shiraz is Australia’s most important red grape variety, and is essential for producing a unique diversity of red wine styles, including some of Australia’s ‘icon’ wines. Anecdotal evidence suggests that a spicy, ‘pepper’ aroma is important to some high quality Australian Shiraz wines. Despite the significance of Shiraz to the Australian wine sector, little is known about the aroma compounds that are the key contributors to the perceived aroma and flavour of premium quality Shiraz wine, and the compound responsible for this distinctive ‘pepper’ aroma in Shiraz had eluded identification until recently. In this paper we summarise the untargeted metabolomics approaches and GC-MS-O experiments employed for the identification of key Shiraz grape and wine sesquiterpenes, α-ylangene (Parker et al. J. Agric. Food Chem. 2007, 55, 5948–5955) and rotundone (Wood et al. J. Agric. Food Chem. 2008, 56, 3738–3744). The relatively unknown sesquiterpene rotundone was identified as an important aroma impact compound in grapes, wine, and common spices with a strong spicy, peppercorn aroma. An aroma detection threshold of 16 ng/L in red wine indicates that rotundone is a major contributor to peppery characters in Shiraz grapes and wine, and to a lesser extent in wine of other varieties, and we explore some factors that influence rotundone concentrations in wine.