Dr Kerry Wilkinson

Dr Kerry Wilkinson

Dr Kerry Wilkinson is employed at the University of Adelaide as a Lecturer of Oenology with the School of Agriculture, Food and Wine. Her research interests concern the chemistry of grapes and wine, in particular the chemical and sensory analysis of compounds of organoleptic significance and the influence of environmental conditions, viticultural management practices and winemaking techniques on their biochemical formation and degradation. Current research projects include: Identification of oak lactone precursors in oak wood; Microbial modification of methoxypyrazines in wine; Smoke taint in grapes and wine; and Characterisation of grape berry tannins.

The research conducted by the Wilkinson group is principally funded through the Grape and Wine Research and Development Corporation (GWRDC) with strong support from the Faculty of Science and School of Agriculture, Food and Wine.

• Research Goals
• Research Opportunities
• Current Group Members
• Research Programme Highlights
• Acknowledgements
• Prizes and Awards
• Key Papers

Research Goals

Our group is committed to new grape and wine chemistry initiatives to bring long-term benefits to the Australian wine industry – through a complementary mix of pure and applied research. In late 2008 we will be relocating to the new Wine Innovation Cluster (WIC) situated on the Waite campus. This state-of-the-art facility brings together all partners on the Waite campus that are devoted to research for the Australian wine industry. The partners include AWRI, CSIRO, SARDI and PROVISOR. The critical mass of personnel coupled with research infrastructure is unique in Australia and allows for rapid, targeted viticulture and oenology research to address industry needs.

Research Opportunities

A number of research opportunities exist for joining our research group especially for projects in collaboration with our WIC partners or other external national and international collaborators. You can join our group as a Summer Scholar, Honours student (half year (12 points) or full year (24 points)), Masters by research (half time or full time), PhD by research, visiting Research Associate or Postdoctoral Fellow. Appropriate academic backgrounds may include: oenology students (winemakers), biochemists, organic chemists, synthetic chemists, analytical chemists (including natural product chemistry), and plant physiology and pathology students. Please contact Dr Kerry Wilkinson directly for further information.

Current Group Members

Dr Kerry Wilkinson Head of group	Kerry Dungey PhD	Anthea Fudge PhD	Rachel Hanlin PhD

Research Programme Highlights

Identification of oak lactone precursors in oak wood.

The most important oak derived aroma compounds are cis- and trans-oak lactone. Oak lactone is present in green (unseasoned) oak wood, but additional quantities can be generated during the seasoning and toasting processes of oak cooperage, suggesting the presence of one or more oak lactone precursors. Recent studies have confirmed the presence of several precursors in French and American oak wood, including ?-D-glucopyranosides. An analytical methods (using liquid chromatography-mass spectrometry) has been developed to enable their quantification in oak and wine. The nature and occurrence of other oak lactone precursors is the focus of ongoing research.

Collaborators: Dr Gordon Elsey and Dr Yoji Hayasaka (The Australian Wine Research Institute).

Researchers: Anthea Fudge (PhD).

Microbial modification of methoxypyrazines in wine.

The ‘herbaceous’ and ‘vegetative’ characters associated with some Sauvignon Blanc and Cabernet Sauvignon wines have been attributed to the presence of methoxypyrazines; potent aroma compounds with detection thresholds (in water) of just 1 to 2 ng/L. At low concentrations (up to 15 ng/L) methoxypyrazines can contribute to the complexity and varietal character of wine, but at higher concentrations they can dominate wine aroma and be considered detrimental to wine quality. This project aims to investigate the ability of certain bacteria and non-Saccharomyces yeast to metabolise methoxypyrazines. If successful, these bacteria and/or yeast could be used as winemaking tools in order to reduce IBMP and associated green characters in wine.

Collaborators: Dr Hentie Swiegers (The Australian Wine Research Institute).

Researchers: Rebecca Kilday (Honours).

Smoke taint in grapes and wine.

Grape and grapevine exposure to smoke can significantly influence the chemical composition and sensory characteristics of wine, causing ‘smoky’, ‘dirty’, ‘earthy’ and ‘burnt’ aroma attributes, i.e. ‘smoke taint’. Current research aims include: (i) identification of the aroma compounds responsible for smoke taint and development of new analytical methods to enable their quantification in grapes and wine; (ii) investigation into the accumulation of smoke derived volatile phenols as glycoconjugate precursors; and iii) evaluation of amelioration techniques, such as membrane filtration and solid phase adsorption, for removing or reducing smoke taint in wine.

Collaborators: Dr Alan Pollnitz and Dr Yoji Hayasaka (The Australian Wine Research Institute), Kristen Kennison (Department of Agriculture and Food, WA), Assoc. Prof. Mark Gibberd (Curtin University).

Researchers: Kerry Dungey (PhD) and Anthea Fudge (PhD)

Characterisation of grape berry tannins

Condensed tannins derived from the grape berry play an important role in wine astringency, bitterness, colour stability and ageing potential. Variation in tannin content, composition and polymer length are likely to affect the mouthfeel and ageing properties of wine. The extraction of grape tannin during fermentation is affected by interactions with cellular components. This research aims to investigate grape tannin and cell wall compositions, and their contributions to wine quality in order to optimise tannin extraction into wine. This knowledge will then be used to develop vineyard management practices for manipulating grape composition.

Collaborators: Dr Mark Downey (The Department of Primary Industries - Victoria).

Researchers: Rachel Hanlin (PhD).

Acknowledgements

The Wilkinson research group gratefully acknowledges the industry partners who generously support their research, including: David Wollan (Memstar Pty. Ltd.), Louisa Rose (Yalumba) and A.P. John Coopers.

Prizes and Awards

• 2006 Science and Innovation Award for Young People in Agriculture, Fisheries and Forestry
  Awarded by the Department of Agriculture, Fisheries and Forestry, October 2006
• Guy Parker Award 2005/2006
  Best paper published in the Water Journal. Awarded by the Australian Water Association Water Journal Committee, August 2006

Key Papers

• Kennison, K.R., Gibberd, M.R., Pollnitz, A.P. and Wilkinson, K.L. Smoke-derived taint in wine: The release of smoke-derived volatile phenols during fermentation of Merlot juice following grapevine exposure to smoke. (Submitted).
• Kennison, K.R., Wilkinson, K.L., Williams, H.G., Smith, J.H. and Gibberd, M.R. Smoke-derived taint in wine: Effect of postharvest smoke exposure of grapes on the chemical composition and sensory characteristics of wine. J. Agric. Food Chem., 2007, 55, 10897-10901.
• Hayasaka, Y., Wilkinson, K.L., Elsey, G.M., Raunkjær, M. and Sefton, M.A. Identification of natural oak lactone precursors in extracts of American and French oak woods by liquid chromatography-tandem mass spectrometry. J. Agric. Food Chem., 2007, 55, 9195-9201.
• Wilkinson, K.L., Kennedy, U.J. and Gibberd, M.R. (2006) Green characters in Cabernet Sauvignon. Oag, D., DeGaris, K., Partridge, S., Dundon, C., Francis, M., Johnstone, R. and Hamilton, R. (eds.) Proceedings of the ‘Finishing the job’ - Optimal ripening of Cabernet Sauvignon and Shiraz seminar; 21 July 2006; Mildura, Australia: Australian Society of Viticulture and Oenology: 60-64.
• Chow, C., Fabris, R., Wilkinson, K.L., Fitzgerald, F. and Drikas, M. Characterising NOM to Assess Treatability, AWA Water Journal, 2006, 33 (2), 74-85.
• Wilkinson, K.L., Chow, C., Fabris R., and Drikas, M. Organic characterisation tools for drinking water treatment - A summary of applicability. Proceedings of the Ozwater Watershed Conference, Brisbane, Australia, 2005.
• Wilkinson, K.L., Elsey, G.M., Prager R.H., Pollnitz, A.P. and Sefton, M.A. Formation of Oak Lactone from 3-Methyl-4-hydroxyoctanoic Acid and its 4-O-b-D-glucopyranosides: A Hydrolytic and Pyrolytic Study. In: State-of-the-Art in Flavour Chemistry and Biology; Hofmann, T., Rothe, M. and Schieberle, P. Eds; Deutsche Forschungsanstalt fur Lebensmittelchemie, Garching, 2005, 213-220.
• Wilkinson, K.L., Elsey, G.M., Prager, R.H., Tanaka, T. and Sefton, M.A. Precursors to Oak Lactone II: Synthesis, Separation and Cleavage of Four ?-D-Glucopyranosides of 3-Methyl-4-hydroxyoctanoic Acid. Tetrahedron, 2004, 60, 6092-6100.
• Wilkinson, K.L., Elsey, G.M., Prager R.H., Pollnitz, A.P. and Sefton, M.A. Rates of Formation of cis- and trans-Oak Lactone from 3-Methyl-4-hydroxyoctanoic Acid. J. Agric. Food Chem., 2004, 52, 4213-4218.
• Lister, T., Prager, R.H., Tsaconas, M. and Wilkinson, K.L. On the Thermally Induced Rearrangement of 2-Alkoxypyridines t

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