Yeasts are integral to winemaking. Without them, there would be no alcohol in wine.
I spent the best part of last week talking with winemaking readers, lovers of good grapes all, who aren’t just interested in yeast, but fascinated by the choices that face a winemaker. The right combination of grapes and yeast is not only important for the finished wine, but absolutely essential in making a finished wine that people want to drink.
Yeasts are unicellular fungi, too small to see with the naked eye. They perform two major functions when it comes to wine. First, they convert the sugars in grapes into alcohol. This miraculous process involves the yeasts consuming grape sugars and changing these sugars into alcohol and carbon dioxide.
Secondly, yeasts impact the ultimate flavors and aromas of the finished wine. Estimates are that of the 1,000 or so volatile (smellable) flavor compounds found in wine, almost half are produced by the actions of yeast (although likely more noticeable in younger, rather than older, wines).
Winemakers only have a couple of chances to “get it right” with every harvest, so it is understandable that they have a tremendous interest in yeast.
The biggest choice for the winemaker is to decide if he or she will allow the yeasts that abound in the natural world to ferment the grapes. Winemakers using this approach might call this “wild” or “native” fermentation.
These yeasts may be unpredictable or may create flavors that the winemaker doesn’t expect. This can be quite fun, or heartbreaking, depending upon the results.
There are also cultured yeast strains available that are more predictable. They can be chosen for their ability to tolerate alcohol, for their ability to ferment the wine until all the sugars are gone, and for their ability to develop desired aromas and flavors.
The more specialized a finished wine, the more likely a winemaker is to select a cultivated yeast to do the work. Some winemakers kill off any native yeasts before adding cultivated yeasts to a fermenting wine, just to avoid problems.
Whatever the choice of the winemaker, the goal is to make a wine that appeals to the target market, tastes good and will sell. Yeast selection, while perhaps a topic that might only interest people who make wine, likely plays a larger role in the wine we drink daily than most of us realize.
In SA Springfield Estate uses yeasts to its advantage and SaleWine.co.za has many of there great wine on Special at present less 20%.
By C Rabb