New barrels unlikely source of Brett

From an article on Decanter.com, we have a theory that new oak barrels are the source of Brett infections in wineries...that "infected wood" has been harvested, and that...

“[Consultant winemaker Matt] Thomson believes that the incidence of brettanomyces has increased in recent years. 'I think it's a relatively new thing in many Old and New World regions,' he said, adding that he thinks the increase is, 'partly down to new wine styles that are low in acidity and relatively high in residual sugar, but also due to increased demand for new oak barrels.' ”

Should this be a concern?
Doesn't nearly everyone use some new barrels somewhere in their production - so, potentially this is a huge issue, right?

For decades wine makers have noticed that Brett infections tend to be caught in wines from new oak barrels - but does that mean the infective yeast was already in the barrel to start with?

I don't think so....

This theory has been in the "folklore" of winemaking for quite a while - it's nothing new (weird that wine makers would employ the "it-can't-possibly-be-MY-fault" type of argument, but I guess that's just human nature...). In fact I ‘ve posted before upon the research work done which showed that 2/3 to 3/4 of wines produced in the EU were contaminated with Brett, and a healthy 50% of all wines were above 425 ppb (the generally accepted threshold for 4-ethylphenol detection for the "average" person), which shows that this is not a “new” problem. But let's delve a little deeper into this subject, and see what we come up with...

• barrels are toasted to temperatures of roughly 200~400°F, and usually this is done with an open flame (though electric heating elements are also used)
• the barrels are likely held at toasting temperatures for 10 to 45 minutes depending on the "house style" toast, or specific toast level requested by the winery, which should be plenty long and hot enough to incinerate any beasties on the wood
• some toasting techniques DO release and/or create sugars from breaking down the wood, some of which may be caramelized by the toasting "style" employed
• the process of toasting can also create low levels of 4-ethylphenol and 4-ehtylguaiacol which are two of the signature compounds of a Brett infection
• these aromas are released in the highest concentrations during the "death phase" (decline) of the population, so detection of the aroma by tasting usually means it is too late in the cycle for prevention - rather you are finding it at the "corrective action" stage
• Brett yeast does seem to like sweeter wines, and lower acidity levels, so there is a viticultural aspect to this problem if fruit is “overly ripe”
• the offending aromas are linked to the presence of caffeic, ferulic and caftaric acids which are at higher levels in less ripe fruit
• contaminated cooperage and other equipment can transfer the dreaded organism from one wine to another undetected, until a later date when the wines "stink"
• vineyards can have a "natural" population of Brett, and equipment used to pick those blocks can bring it into your winery, as well as be a source for cross-contamination of other fruit picked with the same equipment if it has not been properly sanitized beforehand
• infected, but yet undetected, wines can also contaminate larger blends when combined with otherwise uninfected wines

Having seen my share of Brett problems, I can testify to their variable nature (some wines are more noticeably “afflicted” by the yeast, and there is a vintage-to-vintage variation for vineyards as well – though my experience is that past offending vineyards tend to remain infected at some level, that is when the infection can be traced back to a single vineyard or block of fruit). Some varieties like syrah are much more prone to the infection, possibly due to levels of the precursor acids available, and the presence of more sugars attached to the tannins & cyanidins (color compounds). Certainly white varietals are almost never infected (detrimentally) as they don’t really contain those acids, tannins and cyanidins, and therefore can’t be used to produce the offending aromas by Brett.

While true that Brett is noticed more in newer cooperage, this may be two-fold: first, there are already produced compounds of the same nature that Brett produces which may help more people to detect the problem by raising the overall level, and second, there are as previously noted more sugars available for the yeasts to live on (these leach into the wine in the first year of use), which may help larger populations grow – and subsequently generate more of the offending aromas as those larger populations die off. Some varietals have higher levels of the base acids that Brett uses to form the aromas, so are more likely to produce noticeable “faults” later on, and also younger wines still have some sugars attached to their tannin and color complexes (called glycones) which also may be an energy source for Brett when they detach from said complexes as young wines age.

The overall likelihood that the yeast is traveling into the wineries via new cooperage is –at best- doubtful. While it cannot be discounted entirely, it would be surprising since it’d be likely that specific coopers would get reputations as producing those infections, which hasn’t happened to date (I would note that some coopers do have a rep for producing barrels with a Brett aroma from their house toasting styles, but that those barrels are not then always linked to wines which show Brett character or infections later on). Also extremely doubtful is the possible survival of yeast organisms through the toasting process – though that does not mean the barrels couldn’t be contaminated when they were being handled after the toasting as the heads were being put onto them, or during the inspection phase. Important to note that only the interior of the barrels are toasted, and while the entire barrel heats up, only the interior could be considered “heat sterilized” in my mind. The Brett yeasts conceivably could still be on the exterior of the barrel and be introduced by accident when the barrels are handled later. Again, we’d likely see a string of problems all consistently pointing back to a particular cooperage, which isn’t my experience.

Lastly, there is cellar sanitation and “traditional practices”…this is yet another of those modernity vs folklore conflicts…

There is a noted high-end winery in Napa which uses spent lees from their red wines to “paint” the bilges and bungholes of their new barrels red on arrival. Ostensibly, this is used to make an even covering of the barrels, and add a little visual character to their cellar (I have one report that tourists were told the practice “illustrated the winery’s commitment to pay attention to each and every barrel in its care”, whatever that means…). Unfortunately it results in each and every barrel so treated to be twice risked for further infections: once by the fact that other wines which were contaminated but not detected with Brett may now be literally spread all over the new cooperage, and twice by the fact that even if clean wines were applied to the new cooperage, the barrels would now have a food source available for any mold/rogue yeast/what-have-you organism to colonize the barrel and possibly get transferred not only into that barrel itself, but also across to other barrels and blends, etc, as Providence might desire…

It would also not come as a surprise to regular readers that this same winery in the example has been panned by me before, due to the high levels of Brett and other organisms which consistently run through their products.