Have you ever wondered why identical bottles of wine can taste different to one another even if they are from the same vineyard and vintage? New research by Mathabatha Setati and colleagues D Jacobson, U-C Andong and F Bauer from Stellenbosch University, South Africa, may have the answer. Their research, The Vineyard Yeast Microbiome, a Mixed Model Microbial Map published at PLoS oNE showed that different microbes (in this case yeasts) present on the grapes contribute to differences in the flavours and aromas of the wine:
“Vineyards harbour a wide variety of microorganisms that play a pivotal role in pre- and post-harvest grape quality and will contribute significantly to the final aromatic properties of wine. The aim of the current study was to investigate the spatial distribution of microbial communities within and between individual vineyard management units.”
The research team studied the microbial communities present at three vineyards on the same terroir growing the same grape (Cabernet Sauvignon) the Polkadraai region in Stellenbosch, South Africa. Each vineyard used a different method of vineyard management: Organic, Traditional or Biodynamic.
What the team discovered was that the different methods of cultivation had a significant impact on the number and variety of yeasts present. What’s more, they found that different combinations of yeasts could alter the taste of wine in different ways in the same vineyard. This explains why identical bottles of wine from the same vineyard and same vintage can taste different.
They found that the same yeast species dominated all 3 vineyards but the biodynamic cineyard, being the least treated, had the most variety of yeasts leading to the most variety in flavour.
“Cultivation-based methods confirmed that while the same oxidative yeast species dominated in all vineyards, the least treated vineyard displayed significantly higher species richness, including many yeasts with biocontrol potential.”
They also found that within a single vineyard, small differences between vines, such as in temperature or sun exposure, could significantly alter the composition of the fungal community on grape surfaces.
Setati said that “our findings could help viticulturalists and winemakers plan microharvest better, and implement better wine blending strategies to ensure consistency.”
Blending wines has long been practised in Bordeaux to ensure consistency of style and quality of wine and it’s interesting to see the research and science that confirm the reasoning behind this centuries old practice.
In Bordeaux the permitted grape varieties are not grown mixed together but in separate parcels (plots). They are harvested and fermented at different times and the art of the skilled winemaker is to create a blend which keeps the best characteristics of each grape variety whilst weaving them together to craft the final wine. The end result is a wine of consitent quality and balance that brings out the best of the year’s vintage, the terroir and style of the particular vineyard. It’s an intricate process but it does ensure a good wine!