Yeast and wine
In the absence of air, yeast cells transform sugars into carbon dioxide and alcohol. The same yeast is not used to ferment beer or whisky, or to make bread.
Researchers have selected specific strains to make beer, wine, spirits and industrial ethanol (including ethanol-based fuel). The different strains of yeast for alcohol thus have their specific features to adapt to certain substrates (fruit, grapes, grain, beet, malt), enhance particular flavours in the finished product, adapt to certain temperatures, resist high or low temperatures, etc.
In wine-making, yeast plays different roles
What role does yeast play in wine-making? Wine-making uses different strains of yeast that give wines their unique and sought-after taste. Here’s a short wine-making lesson!
Yeasts reveal distinctive flavours (for instance the banana flavour so highly sought after in Beaujolais wine) and also enhance the flavours of certain grape varieties (Chardonnay, Sauvignon, etc.).
Besides active dry yeast for fermentation, wine-making yeast derivatives are also marketed. These products are cellular walls, cellular envelopes, inactive or autolysed yeasts. They are used at different stages in wine production.
During fermentation, they are used to activate fermentation, when alcohol levels are too high and fermentations too slow or difficult.
Finally, in wine maturing, yeast derivatives are used to characterise wines.
Depending on their properties, they can produce a smoother taste or reduce the astringency of certain very tannic wines. Others, with an anti-oxidising power, will prevent white wines from colouring or give a fresher taste to acidic wines.
In the distilling of spirits, yeast is selected to match the substrate used (malt for whisky, grain or even fruit). For neutral alcohol production, the distiller will seek a strain resistant to high alcohol rates but producing very little flavour.