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.