page_title: Yeast in winemaking
section_title: Types of yeasts used in winemaking
hierarchical_section_title: Yeast in winemaking / Types of yeasts used in winemaking
caption_attribution_description: Français&#160;: Tonneau de Vin jaune vitré de la Fruitiere vinicole d'Arbois English: Barrel of fermenting Vin jaune with a cutaway view showing its characteristic yeast film covering called voile, similar to Sherry's "flor", at Fruitiere vinicole d'Arbois
context_page_description: The role of yeast in winemaking is the most important element that distinguishes wine from grape juice. In the absence of oxygen, yeast converts the sugars of wine grapes into alcohol and carbon dioxide through the process of fermentation. The more sugars in the grapes, the higher the potential alcohol level of the wine if the yeast are allowed to carry out fermentation to dryness. Sometimes winemakers will stop fermentation early in order to leave some residual sugars and sweetness in the wine such as with dessert wines. This can be achieved by dropping fermentation temperatures to the point where the yeast are inactive, sterile filtering the wine to remove the yeast or fortification with brandy or neutral spirits to kill off the yeast cells. If fermentation is unintentionally stopped, such as when the yeasts become exhausted of available nutrients and the wine has not yet reached dryness, this is considered a stuck fermentation.
context_section_description: Yeast taxonomy includes classification of yeast species depending on the presence or absence of a sexual phase. Therefore, some winemaking yeasts are classified by their asexual anamorph (or "imperfect" form) while others may be classified by their sexual teleomorph (or "perfect" form). A common example of this is Brettanomyces (or "Brett") that is usually referenced in wine and viticulture text under its asexual classification though some scientific and winemaking texts may describe specific species (such as Dekkera bruxellensis) under its sporulating sexual classification of Dekkera. Unless otherwise noted, this article will commonly refer to the asexual form of wine yeast.
  The most common yeast generally associated with winemaking is Saccharomyces cerevisiae which is also used in bread making and brewing. Other genera of yeast that can be involved in winemaking (either beneficially or as the cause of potential wine faults) include:
  Brettanomyces (Teleomorph Dekkera)
  Candida (Teleomorphs for different species from several genera including Pichia, Metschnikowia, Issatchenkia, Torulaspora  and Kluyveromyces)
  Kloeckera (Teleomorph Hanseniaspora), usually the most common "wild yeast" found in the vineyard. Some species are known as "killer yeast" that produce inhibitory levels of ethyl acetate and acetic acid that can kill off sensitive strains of Saccharomyces cerevisiae
  Saccharomycodes
  Schizosaccharomyces, the only wine yeast that reproduced by fission whereas most wine yeast reproduce by budding.
  Zygosaccharomyces, very alcohol-tolerant and can grow in wines up to 18% v/v. Additionally this yeast can survive in extremely high sugar levels (as much as 60% w/w or 60 Brix) and is very resistant to sulfur dioxide.
  Aureobasidium, particularly the "black yeast" species of Aureobasidium pullulans found in moist cellars that can contaminate aging wine in barrels.
caption: Film yeast on the surface of wine in a barrel of Vin jaune from the Jura wine region of France.
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