New research has shown for the first time how tiny genetic differences in a single microbe help to produce the distinctive variations in taste and odour between wines from different regions.
It was previously thought that wines produced from the same variety of grape by different vineyards get their geographic signature because of environmental factors such as local soil conditions, climate and agricultural practices.
However a new study by biologists from the University of Lincoln, UK, and the University of Auckland, New Zealand, has revealed how sub-populations of a microbe at the heart of the wine-making process can substantially alter the characteristics, or terroir, of the finished product.
Microbes are single-cell organisms found everywhere on the planet. Most belong to one of four major groups: bacteria, viruses, fungi, or protozoa. This new investigation explored how genetically different populations of the main microbe used in the fermentation process during wine-making -- the Saccharomyces cerevisiae yeast -- affects the flavour and aroma of a wine. Much of the character of a wine comes from chemical compounds produced as by-products during fermentation, when sugars from the grapes are converted into alcohol.
The researchers investigated six different populations of the yeast from six major wine growing regions in New Zealand. Using Sauvignon Blanc grapes, they found that concentrations of 39 different compounds derived from yeast during the fermentation process affect the flavour and aroma of wine; 29 of these compounds vary depending on which region the yeast originated from.
Dr Matthew Goddard, Reader in the School of Life Sciences at the University of Lincoln, designed the research and co-authored the resulting paper, published in the academic journal Scientific Reports, alongside lead researcher Sarah Knight from the University of Auckland. The study builds on Dr Goddard's previous work in New Zealand, which for the first time showed that microbes associated with vineyards and wines differ from region to region.
Dr Goddard said: "We believe that this is the first direct experimental evidence showing that microbes help define why you get different wine in different places, or the idea of terroir. The regional distinctiveness of wine plays a major part in its value, and there is a lot of interest in what drives terroir. Classically it was thought that it was down to climate and soils, but our research shows biology also plays a part.
"These findings could be very important because if this is true for wine, it may also be true for other agricultural crops."
The researchers believe that their study could have wide-ranging implications for sustainable agriculture. Until now, microbes have largely been overlooked as a potential driver behind the different geographic phenotypes (physical characteristics) of crops, but these findings highlight the importance of characterising and understanding biodiversity and the services it may provide.
Dr Goddard added: "With a better understanding of the forces driving microbial population and community differentiation, food and agriculture sectors can develop systems to better control and manage these communities, helping to conserve the regional identity of products and hopefully crop health and productivity. We already know that distinct regional variations can have a significant impact on the value of a product and moreover, the methods of farming which maintain different bio-diversities are more desirable as they promote responsible environmental stewardship."
The study concludes that further investigations are now needed to identify whether other species of fungi and bacteria may also contribute to regional characteristics. Dr Goddard specialises in the study of these patterns and processes and he will continue his investigations as part of the Lincoln Institute for Agri-Food Technology, a research institute recently launched by the University of Lincoln to help improve efficiency and sustainability, and to reduce waste throughout the food pipeline, from farm to retailer.
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