Wine microbiology Improving quality from vineyard to glass.
Introduction In 2018 the value of New Zealand wine exports grew, for the 23rd year in a row, by 2.5% to reach $1.7 billion. With a global oversupply of wine the market is fiercely competitive and New Zealand has had to innovate to keep ahead of the competition. There are many opportunities to add value along the wine production chain. Understanding and harnessing the microbiology of the vineyard and ferment presents exciting opportunities to improve wine quality and sustainability.
Past projects and impact Microbes are vital for the production of quality agricultural commodities, affecting product quality throughout the development process. The conversion of grape juice into wine is neither a magic nor industrial process, it is a biological one. Yeasts are the organisms that consume sugars and other nutrients in the juice and excrete ethanol and a host of other compounds that significantly contribute to wine aroma and flavour. In fact, about half of the ‘volatiles’ in wine (the compounds that give a wine its flavour and aroma) derive from yeasts during fermentation. Working closely with industry partners, these are some project examples where our Science is playing an important role: • The distinctive flavours and aromas of New Zealand Sauvignon Blanc have captivated consumers around the world and intrigued scientists eager to explore the variety’s unique characteristics from multiple perspectives. Significant outputs
from the research group includes the development of the first New Zealand derived wine yeast FrootZen®, and the first experimental evidence that microbes can contribute to a wine’s Terroir. • Vineyard Ecosystems, a seven-year research programme led by New Zealand Winegrowers (NZW), represents a shift in the way we look at vineyards, moving away from “firefighting” (issue-by‑issue) based research, to an integrated approach of understanding of the ecology of the vineyard as a whole. Using cutting edge technologies and statistical analyses, the effects of vineyard practices on vineyard biota and the ecosystem services they deliver is being investigated. • The Pinot Noir Programme led by NZWowned Bragato Research Institute, takes an integrated approach to answering the overarching question of how to
increase production of Pinot Noir while maintaining high quality in the finished wines. Using consumer preference studies to establish meaningful measurements for quality that reflect consumer satisfaction, quality chemical markers of premium Pinot Noir can be defined, in turn helping researchers develop assays to guide vineyard management. • The largest research initiative ever undertaken by the New Zealand wine industry, NZ Lighter Wines focuses on the natural production of lighter-inalcohol wines (defined as wines containing less than 10% alcohol by volume). The challenge is not simply to produce highquality, lighter-in-alcohol wines, but to naturally lower the alcohol content without compromising flavour and varietal expression. This research will also benefit winemakers wanting to manage the alcohol spectrum across all wine styles.
Capability and research interests Our group has broad research interests spanning ecological and evolutionary process, population and community biology, and the mechanisms behind the biological and chemical formation of aroma compounds in grape juice and wine. We largely use microbes and wine production as our model system to test a vast array of both fundamental and applied research questions. • Patterns and processes in agricultural ecosystems (including vineyards) • Patterns and drivers of microbial community distribution • Microbial contributions to wine quality and style • Coevolution and yeast/fly interactions • Local and global population genetic patterns and processes in Saccharomyces cerevisiae • Elucidation of the pathway/s to volatile thiols in white wine • Pinot noir fermentation dynamics and aroma chemistry • Investigation into yeast genes linked to fermentative lag phase • Wine chemical features linked to positive reduction and minerality in Chardonnay wines and the potential role of yeast
The University of Auckland
• Polysulfide behaviour in wine
Meet the team Prof Mat Goddard is based at Lincoln University (UK) and has a joint appointment at the University of Auckland. He finds the workings of the natural world wonderfully curious and is constantly amazed by the adaptations that organisms display. He is interested in trying to understand the underlying biological rules that apply to all populations, considering the ecological and evolutionary forces shaping a population’s genetic pool. Dr Sarah Knight is passionate about what molecular tools can tell us about the ecology and evolutionary history of populations. She has been working in the microbial space, where the performance of these communities has wide ranging implications for the health of our natural ecosystems, and for the success of many industries, including the New Zealand Wine Industry.
The University supports economic growth locally and nationally through innovation and entrepreneurship, creating quality jobs and high-value businesses, producing graduates that contribute to and strengthen our economy and society, to the benefit of all. The University of Auckland is New Zealand’s world-ranked university. It is the leading New Zealand university in the QS World University Rankings 2019* and the highest ranked New Zealand university in the Times Higher Education World University Rankings.†
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Dr Rebecca Deed’s current research areas of interest are focused on using a combination of techniques in molecular biology and analytical chemistry to understand the mechanisms behind the biological and chemical formation of aroma compounds in grape juice and wine, as well as understanding yeast metabolic pathways leading to good fermentative ability.
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