Wine Glossary
Definition: Brett or Brettanomyces
The wine character described as "Bretty" comes in various forms. It is the combined result of the creation of a number of compounds by the yeast Brettanomyces bruxellensis, and its close relative, Dekkera bruxulensis. The three most important aromas of Brett are a Band-aid®, antiseptic and horse stable smell or a pleasant aroma of smoked bacon, spice or cloves or an unpleasant smell of sweaty animals, cheese and rancidity. Other characters associated with Brett include wet dog, rotting vegetation, and plastic. Brettanomyces proliferates under warm cellaring conditions. Twenty degrees C is an ideal temperature, with even small reductions in temperature seriously hamper its growth. It is widely acknowledged that the majority of wines with Brett character, became that way during the period of barrel maturation, particularly if second use (or older) oak barrels were used. Brett can colonize a barrel between fills, and can begin to reproduce when the barrel is refilled with new wine. One final matter concerning Brett is rarely mentioned. It occurs almost exclusively in red wines. Why is this so? Red wines have a much higher level of tannin like substances called coumaric and ferulic acid than do white wines as they are extracted from the skins of grapes during red wine fermentation. Is the action of Brett desirable? The answer depends on degree. As well as producing a band-aid aroma, Brett can create an array of 'interesting' smells that can excite those that are inclined to be excited by them.
Source: Australian Society of Wine Education