Bushfires are causing a headache for Australian winemakers.
If not in my eyes, smoke has certainly been on my mind in recent weeks, as ash from the eruptions of Chile's Puyehue volcano almost saw me stranded in Marlborough then made a wine trip across the Tasman touch and go. When I eventually arrived in Australia, I discovered smoke was also causing concern to the country's winemakers - not from a volcano, but from bushfires that have tainted wines and cost the Victoria region alone more than A$300 million ($388 million) in the past five years.
Given that the term smoky is often used as a positive flavour descriptor in wines, you may ask why a whiff of something burnt is such a bad thing. I had the opportunity to sample some fire-affected examples after the devastating 2009 bushfires in Victoria. Believe me, rather than delivering something acceptably charry, the experience was more akin to imbibing from an ashtray.
Some grapes have naturally smoky nuances: however most smoky flavours come from a wine's contact with wood during its fermentation or maturation. In traditional barrel-making, the staves are shaped by being heated over a fire, which imparts a toasty or charry character transmitted to the wines matured within them in their first years of use.
Nowadays, winemakers can specify the level of "toast" they require in their barrels. This ranges from low to high, with the upper end often able to imbue a wine with overtly smoky roasted notes.
While judging the appropriate amount of barrel-derived smokiness is crucial in making well-balanced wines, the flavours wood provides are largely positive. However, when grapes are exposed to smoke, even for as little as half an hour, it appears, the by-products prove far less palatable.
Given the run of bushfires in Australia over the past decade, this is something their wine industry has become increasingly aware of. In an attempt to better understand smoke contamination and tackle the issue, the Victorian Government has just pledged A$4 million for research.
The Australian Wine Research institute has been conducting its own studies. It's already discovered that the "l'essense de cigarette butt", which has been identified as guaiacol, penetrates the grapes' skins and can't be removed simply by washing the ash off affected fruit.
Different grapes and wine styles appear to be affected to varying degrees. In red wines, which are fermented with their skins, its extraction is difficult to avoid. But it can also seriously impact on the quality of white wines.
Anecdotally it appears certain varieties, such as pinot noir, sangiovese and cabernet sauvignon, are most susceptive to the taint, while the merlot and shiraz are proving more resilient.
Once the stink is there, it's hard to shift and indeed appears to get more intense in a wine over time. The AWRI has experimented with a procedure more commonly used to decrease alcohol levels in wines, called reverse osmosis, which has had some success in sucking out the smokiness.
Another option is to filter or add a fining agent. I've tasted some of the results of this technique and the wines sure didn't make for exciting drinking. As well as removing the taint, it indiscriminately spirited away a significant proportion of the positive characters as well.
As I awaited word on my ash-affected aviation, my imagination started to wander. Bush fires smell bad, but maybe subtle manuka smoke might make for a more appetising infusion?
I'd heard of a winemaker growing flowers among his vines in an attempt to transfer their fragrance to his fruit. At the time I'd thought the idea possibly inspired by something more intoxicating than bushsmoke, but in the light of recent findings I just may have to reassess.
THE RIGHT NOTES
Martinborough Vineyard Martinborough Chardonnay 2009 $40
Classy oak has imparted an incense-like character to this elegant, taut chardonnay that's coiled round an intense core of citrus and mineral. (From Caro's, Fine Wine Delivery Company, Glengarry, Liquor King.)
RIPE AND SPICY
Lake Hayes Central Otago Pinot Noir 2009 $30
Big, rich, ripe and spicy black cherry fruit is the focus of this robust Central pinot, which also exudes some seductively subtle floral characters reminiscent of honeysuckle and jasmine. (From Liquor King Ponsonby, New World Victoria Park & Devonport, Hillsdene Wine Cellars, amisfield.co.nz)
Brennan Gibbston Central Otago Gewurztraminer 2010 $28
A deliciously delicate off-dry gewurztraminer with pure nashi pear fruit infused with notes of rose petal, lychee, quinine and clove.