Hi Ric,

Paul Henshke has done a lot of work with this at Waite, it would be worth speaking with him when you next go to SA on tour.

With regard to our previous correspondence on the subject of Brett – look, this is a yeast – if the wine is micron filtered it will be removed entirely along with all other yeasts. However, I have seen many, many wines where they were closely filtered, yet still retained the by-products and effects of Brett’ spoilage. No one really understands fully what is going on. What we do know is that this spoilage is almost ubiquitous the world around. Yes, it was a major component of the Hunter sweaty saddle (along with mercaptans) and is endemic in old cellars.

Once resident in a winery it cannot be “cured” – only managed.

Considerable research has been done both here in Blenheim and in Napa to attempt to source the main area of contamination. Sundry white-coats have traditionally blamed the vineyard, however this is apparently NOT the source. Though very persistent within a winery it appears as though it cannot survive in the open field (in its current form). The greatest source of entry appears to be in new oak barrels. Old oak barrels of course are a continuing source, but the main contamination is in brand-spanking-new oak. Many wineries here (in NZ) are now treating their new oak with ozone (effective in most cases), before allowing it into the barrel-room. Apart from this is the quarantine and culling of any barrel (and its contents) as soon as Brett’ is detected.

There is a current move toward “non-filtered” wines. Fine, something of the flavour can no doubt be removed by close filtration but there is an increasing risk of spoilage.

As a pragmatist, I have to ask if a winery can afford to have an “off” wine in the market place these days? I strongly doubt it – with the choice and the general cleanliness of wines these days, why would a punter go back to a brand that was spoilt? The days of iconoclastic wines, the old Belbourie springs to mind, are over. Perhaps the right word is not iconoclastic, rather “deviant” might be better (esp. Belbourie).

I hosted XXXXXX XXXXXX for a couple of days in February, and was saddened to see that he is trying to go down the “wild-yeast” ferment and “build character” into his wines. That may be fine for some, but I found all of them had significant spoilages. The Xyzabc was acetic (at the very least ethyl acetate) and his other two reeked of H2S and worse, diethyl mercaptans. I am quite sensitive to sulphides and so struggled to cope. It was a great pity because the underlying fruit showed great promise – not the blowsy fruit from the Southern Vales, but a better structure that is typical of WA. The other negative was the high pH, although this is common in Aus reds.

There are few truly wild yeasts. Most are resident in the winery, on the walls and in the air. Kloeckera apiculata starts many of these ferments (earthy/wet leaf-mould) and will continue if there is insufficient S. cerevisiae to dominate it. Brett’ comes in to finish the job.

The main S. cerevisiae wild yeasts are therefore permanently resident in the winery – usually the most frequently used strain. As most wineries use some form of  S. Bayanus  (EC 118, aka Pris de mousse) as a Killer yeast (for stuck ferments) and as this is hugely viable, it is most often this yeast that is the resident “wild” one.

So in reality the wild yeast are “non-inoculated” ones and with the exception of Kloeckera, they are far from “wild”.

Cheers,
Murray

Vinifera Services
PO Box 1099
Blenheim, Marlborough
New Zealand