Wine Words: Brettanomyces

Brett (or Brettanomyces to give it its full name) can be quite a controversial word. Readers may have heard a wine described as 'bretty' or having a bit of 'brett." Do you know what Brett means?

Brettanomyces is a Yeast
Brett is a natural yeast, found to some degree in all winemaking regions. In general it is considered a spoilage yeast - i.e. unlike the good yeasts which convert sugar into alcohol to make wine, brett creates less desirable outcomes in a wine. However opinions differ, and some people consider that low levels of brett can in fact add a dimension of complexity to a wine.

Brett's Favored Environments
Brett thrives in certain environments. Anywhere you have ultra-ripe grapes, warm fermentations, high alcohol wines, residual sugars, low acidities and high pH levels Brett can have a field day. It is less usual to find 'brett' in white wines, as white wines typically have higher acidity and lower pH levels.

Under the right conditions Brett can really settle in and infect a winery and its wines. While brettanomyces is most associated with a winery's barrel room (it loves dirty old barrels!) it can harbor in many other places around the winery such as the receiving and fermentation equipment, the crushpad area and even in the fermenting wine itself.

The Smell and Taste of Brett
When the Brett yeast acts on wine, it produces a number of by-products, the most important of which are the volatile phenols. While harmless, these volatile phenols impart a barnyard, sweaty, horsey odor and flavor to a wine.

When in small quantities, some attribute the aromas and flavors to terroir, but in large doses, 'brett' totally overpowers and /or dumbs down the fruit aromas and flavors of a wine.

Brett - Is it a Friend or Foe?
For a long time, particularly in old world winemaking regions, Brett was almost considered part and parcel of the 'terroir'. Today, more winemakers consider it a sign of poor winemaking and /or less than ideal winery sanitation conditions.

Additionally some people are more sensitive to Brett than others, and as indicated above, some actually like a little 'brett' aroma in a wine, while others cannot abide even the merest hint of the beast.

Managing Brett
Hygiene throughout the winery, pH management as well as judicious use of sulphur dioxide are the most common ways of managing infestations of Brettanomyces.

Mary Gorman-McAdams, MW (Master of Wine), is a New York based wine educator, freelance writer and consultant. In 2012 she was honored as a Dame Chevalier de L'Ordre des Coteaux de Champagne