Vineyard Microbes May Create Wine Variations
Wine gets it flavor from the grape itself, the climate of which the grapes are grown, and the winemaking process- so vineyard management is a crucial part in contributing to the final aromatic properties of a wine. With this, researchers are finding that a wide variety of microorganisms are also contributing to pre- and post-harvest grape quality and will essentially influence the final taste of a wine.
Researchers at Stellenbosch University in South Africa investigated the spatial distribution of microbial communities within vineyards of different farming systems- organic, traditional, and biodynamic.
The data demonstrate that farming systems have a significant impact on fungal diversity but more importantly that there is significant species heterogeneity between samples in the same vineyard.
"In the wine industry, the fungal communities on grapes are especially important. The microbial species present on the berry may contribute to the fermentation process, and therefore the aromatic properties of the resulting wine", the authors explain.
Cultivation-based methods confirmed that while the same oxidative yeast species dominated in all vineyards, the vineyard that was least treated with fungicides and pesticides displayed significantly higher species richness. The data confirm previous results that biodynamic farming, (organic farming that emphasizes the interrelationships of the soil, plants, and animals as a self-sustaining system) leads to a higher microbial diversity. They found that the same yeast species dominated in all vineyards, but the least treated vineyard had more variety of fungal species than the other two.
Also, yeast species distribution is subject to spatial fluctuations and samples of grapes that were harvested at the same stage of ripeness showed differing microbiota due to the different sections from where they were collected in the vineyard.
The research shows that intra-vineyard variability can be attributed to considerable amounts of both inter- and intra-row spatial heterogeneity. This heterogeneity could be in part due to differences in immediate vine ecosystems and variation in inter-vine and intra-vine microclimates. For instance, the relative position of vines within the vineyard results in differences in the amount of sunlight and temperature, which in turn would affect the growth and pigments of the grapes.
From a wine-making perspective, the data suggest that spatial fluctuations in microbial diversity might have a significant impact on downstream processes and analyses. The study's findings could help viticulturalists and winemakers plan microharvest better, and implement better wine blending strategies to ensure a consistent batch and brand of wine.
Read the complete research article at PLOS ONE.
Wine grape image via Shutterstock.