Brettanomyces, often shortened to Brett, is a genus of yeast that can grow in wine and produce volatile phenolic compounds associated with aromas such as barnyard, leather, horse sweat, medicinal bandage, smoke and spice. It is commonly regarded as a wine spoilage organism, although the perception and acceptability of low levels vary among producers and tasters.
Brettanomyces can survive in winery equipment, barrels and other cellar environments. It may develop during fermentation or ageing, particularly when hygiene and microbial controls are inadequate. The compounds it produces can alter the wine’s aroma and mask fruit character. Some wines show a small amount of Brett-derived character without being considered undrinkable, but excessive levels are generally a fault.
Common descriptors include barnyard, horse stable, leather, medicinal bandage, smoky spice and sometimes animal or sweaty notes. The aroma can vary according to the compounds present and their concentration. It should not be confused with deliberate oak, smoke or earthy complexity.
Wineries manage Brett through sanitation, monitoring, appropriate sulphur dioxide use, filtration where suitable and careful barrel management. Once established, Brett can be difficult to remove without affecting the wine’s texture or flavour.
Example: a red wine with strong horse-sweat and medicinal aromas, alongside diminished fruit, may show excessive Brettanomyces character.
Chef’s note: low-level Brett character can be debated, but a pronounced medicinal or barnyard profile that overwhelms the fruit is generally a wine fault. Assess the wine rather than assuming every earthy or leathery note is Brett.
This term is one of hundreds covered in depth across OCS courses, learning paths, and 1-on-1 coaching with Chef Eric.
