Screening brettanomyces
Methodology for the Screening and Isolation of Brettanomyces
in the Grape: plot-scale application
Conclusion
This study has, therefore, highlighted a method for screening and isolating Brettanomyces directly from grapes on the vine. It is simple to implement (conventional microbiology).
Applications and follow-up procedures carried out for several years now, confirm the actual presence of the Brettanomyces yeast on the grape, signifying a potential source of
contamination for downstream winemaking processes. Suitable, preventive methods must now be considered for harvesting (adequate sulphite application) in order to minimise the amount
of contaminant entering the cellar.
Although non-quantitative (because the initial population present on the surface cannot be estimated), this method nevertheless detects the presence of yeast even at very low, initial levels.
The work carried out on the target plot has, moreover, shown that, within a given plot, the presence profile of the contaminant could be influenced by environmental factors. Suitable growing/crop practices must be considered in order to minimise the risk of the presence of the yeast on the berries. Moreover, a sorting procedure capable of distinguishing between bunches of grapes with a potentially strong presence (damaged bunches) can minimise the number of contaminant yeasts collected at harvest.
Acknowledgements
We wish to thank all those people who took part in this study, especially personnel from Oenodev and the Cave Coopérative de Buzet, and the owners and managers of the plots of land, which provided essential support for our study. We would also like to thank J-L Cheval, l'Institut Départemental d'Analyse et de Conseil de Nantes (Departmental Analytical and Advisory Institute, Nantes) for their contribution during genetic identification studies.
(1) Pascal Barbin, Pierre Strehaiano, Patricia Taillandier - (2) Jean-François Gilis
(1) Chemical Engineering, Bioprocesses and Microbial Systems Laboratory
(2) Oenodev
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