Selected yeasts are commercial yeasts (Active Dry Wine Yeast) or specially isolated yeasts from the property's grapes which have been propagated to be used for inoculation.
Yeast is responsible not only for transforming sugar into alcohol but also the aromatic precursors in the grapes into aromas and flavours. Inoculation remains the best method for safe alcoholic fermentation.
4.1.3.b Use of selected yeasts for fermentation
Is it necessary to use specific yeasts?
ADWY (active dry wine yeasts) have different properties and vary in their ability to adapt to a given environment. The classic example is their ability to withstand high levels of alcohol. When the potential ABV is projected to be above 14.5, it is recommended to use yeasts that are selected to withstand this kind of environment. Otherwise, there is a real risk of a stuck fermentation.
Other criteria should be taken into account, such as the tendency to produce volatile acidity, sulphites and the aromatic profile towards which the vat is oriented at the end of fermentation.
What quantity should be added?
For ADWYs, it is sufficient to follow the supplier's recommended doses. In general doses are between 10 and 20 g/hl.