Tourists flock to Napa Valley and Bordeaux because there is something special about the wines produced there. In the past, scientists have attributed the unique flavor and aroma of these wines, known as terroir, to environmental factors such as soil and climate. But wine variety may be most heavily influenced by a previously overlooked factor: genetic differences in populations of the Saccharomyces cerevisiae, the principal yeast responsible for fermentation. For the first time, scientists at the University of Auckland and the University of Lincoln have experimentally linked microbes to the subtle nuances of wine.
Though they may not evoke the sun-bedecked vineyards of France, microbes are critical to every step of the winemaking process. Their ability to ferment sugar from grapes into alcohol is well known. But microbes also secrete an array of secondary molecules that serve an interesting function in the process of winemaking. Perhaps the most significant of these secondary molecules are volatile organic compounds, which evaporate at room temperature and affect he smell of wine.
In a survey of six wine-producing regions of New Zealand, the team of scientists led by Sarah Knight determined that there are significant differences in volatile compounds produced by the regional sub-populations of S. cerevisiae. Variation in the concentrations of these compounds is essential in shaping the unique, local identity of wines.