Controlling alcoholic fermentation in mixed microbial communities: towards a new technological approach in cider-making and oenology

The ultimate aim of this project was to provide the ‘wine’ and ‘cider’ sectors with the means to better control the fermentation stage, whilst taking into account the risk of excessive standardisation resulting from an over-simplification of the yeast flora. The aim was to understand the interactions between yeasts of the genera Hanseniaspora and Saccharomyces under cider-making and winemaking conditions, with a view to exploring their use in mixed flora to produce more aromatic end products. Pilot trials and tests in cider-making workshops enabled the conditions for using mixed-flora technology to be defined and validated up to a pre-industrial stage. In terms of improving the aromatic qualities of the wines, the batches produced demonstrated the significant potential of non-Saccharomyces strains. Tastings carried out at various stages of wine production by trained panels show that wines resulting from mixed flora fermentations are generally appreciated for their aromatic complexity and flavour characteristics.