Brett - An explanation needed please

[GrahamB]

Ric

In your recent article on Brett in HoG you quote

The winemakers should be talented enough to pick it up prior to release and if it is picked up early enough, it can be eliminated prior to bottling.

How is Brett removed? Are there some talented winemakers or scribes out there who can explain the removal process.

Ta

Graham

[Neville K]

Graham,
As I understand Brett, removal is not unlike asbestos removal: painstaking, thorough purging under clinical conditions. Specialists only need apply.
Did you read this article from last week's Epicure? You might have to register, but it is free.

http://www.theage.com.au/news/Epicure/B ... 84869.html

Neville K

[Smithy]

Brett is a yeast that can get going in the bottle under the right conditions, namely low SO2, higher pH, and bugs there to start with.

Like all yeast time and temperature effect how much Brett there will be.
Sterile filtering will obviously take out all the yeast cells, but the spoilage charachter may already be there (sort of closing the stable door after the horse has bolted stuff)

The trick is not to get it in the first place, and the AWRI has been world leaders in teaching Aussie winemakers how to stop Brett.
Cheers
Smithy

[TORB]

Here is another one which may help explain it.

http://www.vwm-online.com/Magazine/Archive/2001/Vol27_No5/Brett.htm

[Guest]

Smithy was correct is his explaination. The culprit produced by these Brettanomyces yeast is 4-ethyl-phenol, which I described as smelling exactly like that brand of bandaid called Elastoplast.

Also as Smithy stated, it thrives in low SO2, high pH situations. The most common cause of Brett spoilage in wines though, it when you combine these factors with older oak (how many unoaked whites have you seen with Brett?). The Brett yeast population grows over time in barrels if not washed and stored correctly, and it is almost always (though I have seen it in new oak barrel too) found in wines stored in 1, 2 and 3 year old oak barrels.

I also notice a higher incidence of Brett spoilage in wines from warmer areas such as the Hunter and WA - or more specifically, areas without cold winters. Obviously in areas where the winters are cold, it makes it very hard for yeast to grow in the wine. The Hunter and Margaret River do not get extremely cold in the winters, the wine in barrel stays warmer, and hence any population of Brett yeast is able to grow.
Cheers

[guest]

Most wines are a blend of barrels and/or vats (unless they were all matured in a single barrel, or a single vat) and so the trick is to detect the brett-affected barrel(s) and simply not include it/them in the final blend. This is the best way for an experienced, on-the-ball winemaker to keep brett out of his/her wine - apart from massively increasing the so2 and/or sterile filtering. Once the wine is in bottle, it's a whole lot harder to then get the brett out of course, and it's then that the winemaker should decide to do one of the following: a) declassify the wine, b) reduce the price, c) stand up and say: it's got brett, but I still think it's mighty good. All of these moves are potentially acceptable, depending on the wine. The only move that is not acceptable is to release a markedly bretty wine and then deny that it is so.

[Guest]

Has anyone else noticed Brett in Henschke wines recently?? The last few vintages of the Mt Edlestone Shiraz definitely have Brett

[GrahamB]

Thanks all for the responses. Some good reading here which I hope will give me a better understanding of Brett.

I am still holding 1 bottle of a Barossa Valley Estates Shiraz, originally destined for the Canadian market, which I believe is Brett affected. Don't know what I will do with it but if someone asks what Brett is like, I can give them an example.

Graham

[Guest]

Just to contribute... Brettanomyces is a spoilage yeast and has recently been reclassified Dekkera (the once thought of sexual form). It is actually thought that there are three major metabolites which cause Bretty characteristics in wine, I will only dwell on two (and briefly at that). 4EP and 4EG, 4 ethyl phenol and 4 ethyl guiacol, depending on concentration can contribute anything from clove like to sweaty horse saddle right through to the previously mentioned band-aid character. It is also important to note that these compounds have incredibly low thresholds. Its the metabolism of lysine (primarily) which leads to the production of these compounds.

Brettanomyces yeast have varying tolerance to sulphur, acidity and alcohol, all of which play the role of antimicrobiality during wine production. The major area of contamination is wood, where the mechanism of survival is not fully understood, however that is the most prevalent source of Brett contamination. It has been recommended by certain bodies that the only effective way to eliminate Brett from a barrel is 80 degree hot water wash for a set period (I think its 5 min - cant remember). This however may not be completely effective, as wood is a porous media, the transfer of wine through a stave over the period of a period of time (say three months) will be far greater than the contact heat of 80 degree water through a barrel for a much shorter period (ie. minutes). At the endo of the day, if there is a Brett problem in a cellar its very hard to eliminate.

Personally, I think Brett in low concs, is complexing enough to lift a wine, there is however a very thin line between complexing and faulted.

Hopefully I havent repeated too much of what else was posted previously.

Cheers.

[TORB]

OK, now I have got a question. How can you differenetiate between clove from French oak and clove from Dekkara?

[Guest]

It doesn't take much to send samples to the AWRI for analysis of 4-EP, 4-EG and IVA....which a lot of wineries do.....maybe they sent the sample and still decided to market the wine.....unlike Cape Mentelle a couple of years ago...who knows.
I tried three bottles of '98 HOG last week all differnet and ranging from fangoriously Bretty to bloody magnificent.....whatdoyado??