This is not the start of a teenage letter, not does it refer to the kid who picked on me in high school. Instead this “Brett” is much scarier, harder to get rid off and is the bain of many a New World Winemaker.
“Brett” is short for Brettanomyces, a non spore forming genus of yeast in the family “Saccharomycetacea” The genus name “Dekkera” is interchangeable with Brett as it describes the teleomorph or spore forming form of the yeast.
This yeast is acidogenic and when grown on glucose rich media, produces large amounts of acetic acid [it helps to be married to a micro-biologist with a Ph.D.]
Referring to Brettanomyces here on out as simply Brett.
When present in minor amounts, departing from perceived normal characteristics of a wine, it is simply perceived as a flaw but if this character becomes excessive [which is dependent on the particular taster], the wine can be deemed to be faulty or defective. This could be attributed to poor winemaking or improper storage conditions.
Some of the most famous wines have a whiff of Brett that tasters refer to as character or “Terroir”, think Chateau de Beaucastel for example. But one person’s pleasure is another’s disdain. Essentially this could also be the definition of a New World Winemaker and one from the Old World. While I drink my weight in French wines [not the only wines that have Brett character, tried South African and Californian infected wines too], I would be bitterly upset if that character were to be present in one of my wines at Keswick.
It is believed that Brett can be introduced into a winery by insect vectors such as fruit flies or by purchasing infected barrels, as such Brett is most common in red wines aged in oak. The ability to metabolize the dissacharide cellobiose, along with the irregular surface of a barrels interior, provide ideal conditions for Brett growth.
Okay, enough of the mumbo jumbo and fancy words, what does a wine infected with Brett smell and taste like?
This yeast can produce an array of metabolites when growing in wines, some of which are volatile phenolic compounds, which together are often refered to as Brett character. The compounds responsible for the various sensory characters are;
4-ethylphenol [barnyard, band-aid and manure] YUCK
4-ethylguaiacol [bacon,spice and cloves] YUM
isovaleric acid [sweaty leather, cheese] YUCK AGAIN
Depending on what compound is the most dominant in the wine, the consumer might find it desirable or totally repulsive. Note that none of the above descriptors are fruit, and in the new world where fruit is king [both in aroma and flavor] Brett character is viewed with a fair amount of disdain, with all efforts taken to ensure it never enters into the winery.
So the obvious control os to never ever get it into the winery, but it if it does? Well a new marketing strategy might be in order along with heavy doses of sulfur, sterile filtration and the addition of dimethyl dicarbonate, all of which in my opinion reduces wine character. Ask any of my interns who have worked a vintage with me, all I do is stress cleanliness and if that means cleaning up the winery at 2am instead of heading home after a long day of processing, then so be it. Why? Well even though I love drinking wines with a bit of that Brett character, I HATE BRETT in any wine that I make.
Disclaimer – the opinions of this blog reflect those of one crazy winemaker with a wide variety of tastes and thus should not be taken seriously. Trust your own palate and decide for yourself.
The next blog, Wines from my home Country