What's going on when you open a bottle of wine and smell . . . Band-Aid? Welcome to the world of brettanomyces (aka Brett). This character in our script is a wild yeast that sometimes makes it into your wine -- usually your reds, but sometimes your whites. Brett plays a leading role in the nightmares of most winemakers because it's like a feisty two-year-old child: uncontrollable yet full of potential.
Brett is not necessarily an off-flavor (in palatable amounts). If you were to make a list of Brett's positives, you could include beguiling earthy aromas such as rustic barnyard, spice and horse saddle. When I find Brett to be in a good mood, I am mentally transported to a dark, dusty stable filled with horses, hay and barnyard animals. I hear the horses snorting and pawing at the earth and hens clucking nearby. Perhaps a pig runs through the scene of my imagination. And I am in my happy place -- much like the five-year-old I was when hanging out with horses in my rustic neighborhood of Vista, California. Sidebar: The salt-licks were exotic but not off- menu.
However, Brett has a dark, evil side. Off-flavors that make it impossible to enjoy your wine might include the aforementioned Band-Aid, which I recently encountered in a 2014 Equis from the Saint-Joseph appellation in the Northern Rhone region. The Band-Aid aroma was mild but distracting in what otherwise was a delicious wine. See my review at Vivino. An unruly Brett wouldn't think twice about offering up medicinal, metallic, rancid cheese and other off-putting aromas.
Brett can make itself at home at any stage in the winemaking process, from the grapes to the winery and the barrels. Improvements in cleaning technologies have made it possible to avoid Brett, but these Yeasty Beasties sometimes find a way in.
As a brewer of beer, I find Brett an intriguing dancing partner -- racy, but don't turn your back on him. Brewers are increasingly seduced by the potential of Brett, but it takes a racy type of vintner to embrace the potential of Brett. Many aromatic compounds are shared in the fermented products of wine and beer, so when I study one, it usually helps me with the other. However, in beer, a band-aid aroma is typically associated with Chlorophenols, which is the result of chlorine-based sanitizers like bleach. This differs from wine, where we look to naughty Brett as the villain. Or the hero.