Over the centuries, many new yeast species and strains have been discovered, bred and then chosen to perform specific tasks such as rising bread, producing alcohol, biofuels and probiotics. This is due to each strain having unique characteristics causing them to perform better in certain situations compared to others.
Baker's yeast is the common name for yeast strains used in bread and other bakery products, serving as a leavening agent which causes the bread to rise (expand and become lighter). Fermentable sugars within the bread are converted into CO2 and ethanol which causes the rising effect.
Although bakers and wine yeast are mostly from the same genus and specie, Saccharomyces Cerevisiae, they are all different strains. Different strains will have different fermentation capabilities, including by-product production, certain tolerances towards alcohol concentrations and osmotic stress and the type of raw material used for fermentation.
Tolerance towards alcohol:
Wine yeast has a high alcohol tolerance for it can survive conditions up to 15 -16 % v/v. Bread yeast, on the other hand, can probably produce alcohol up to 6-8 % v/v. This means that bread yeast cannot survive the high alcohol content desired by winemakers. If you are producing beer, cider or any low alcoholic strength drinks at home, bread yeast will be more than capable.
Osmotolerance:
Baker’s yeast are normally not known to have a high osmotic tolerance (not able to withstand high sugar concentrations). Excess sugar, as well as other dissolved solids in a fermentation medium, will pull water out of the yeast cells, desiccating and killing them. This will result in stuck and incomplete fermentation. Grapes are known for having a natural high concentration of sugar at full ripeness and this might be above what bread yeast can tolerate.
By product production:
During fermentation, many other products are produced, but in much smaller quantities. These products usually contribute to the aroma and flavour of your fermented product. In the wine industry, the aromatic profile of the wine is extremely important and thus, yeast selection is done thoughtfully. Bread yeast is not known to be uniquely aromatic compared to wine yeast strains and would thus not be able to satisfy the required aroma complexity for wine production.
Raw material:
Bread yeast is used to ferment grains whereas wine yeast is used to ferment fruits. The composition of fruits and grains differs, which includes the type of sugars and nutrients naturally present.
Clarity of fermented product:
As fermentation slows down, you will notice wine yeast clumping together and settling at the bottom of the fermenter causing the wine to become clear - a process called flocculation.
Baker’s yeast, on the other hand, does not clump and flocculate as readily as wine yeast. Instead, it slowly settles to the bottom as a fine haze that will not be able to be cleared out completely. Settling can take days or even weeks. Wine made from baker’s yeast will thus remain hazy for long periods, making it unattractive for consumers while imparting a yeasty taste.
There are several other issues with using bread yeast to make wine, but these are the most important. Can you use Baker’s yeast to produce wine? Technically yes you can, but would it be something you would want to drink? Probably not.
