Sunday, August 15, 2010

Going wild in the west; trouble brewing

Vanya Cullen in her biodynamic vegie patch
A dispute is bubbling away in Margaret River that could change the way we think about the importance of wild yeasts in winemaking.

Local developer Murray Burton wants to build a micro-brewery and cellar door complex next to Cullen, one of the region’s best-known vineyards. Cullen, who ferment all their wines using the wild yeasts present in their vineyard, are urging the Busselton shire council to reject the application, arguing that rogue beer yeasts from the brewery would find their way into the grape ferments, and change the unique character of the Cullen wines.

The developer argues that the proposal meets planning regulations and that the beer yeasts will be contained, but in March, council rejected the brewery on the grounds that it ‘may jeapoardise the agricultural use of adjoining land’. The matter went to the appeals tribunal for mediation, an expert witness report was commissioned, and council is due to discuss the matter again this week (see UPDATE, below).

In April, Cullen sent some cabernet grapes to Curtin University’s winery for some fermentation trials to see whether different yeasts produce different results.

The grapes were fermented in four small batches: one was allowed to ferment with just the wild yeasts that came in with the fruit; one was inoculated with EC118, a commercial cultured yeast strain commonly used in Australian wineries; one was inoculated with Safale, a beer yeast; and one with a combination of EC118 and Safale.

The wild yeast ferment took the longest to start, and then proceeded slowly until all the sugar had been converted to alcohol and the wine was dry; the cultured wine yeast started almost immediately and fermented to dryness quickly; the combination of beer and wine yeasts was similar, if a little slower than the straight EC1118; but the beer yeast stopped fermenting the grape juice before all the sugar had been converted to alcohol (a headache if you’re trying to make top-class cabernet).

The wines were tasted blind by the researchers: those which had been fermented using beer yeast had aldehydic, yeasty characters; the one fermented using cultured wine yeasts tasted clean but dull; the wild-fermented wine showed brighter, more elevated fruit characters.

Some scientists believe that naturally-fermented wines show more complex, distinctive flavours because various yeast strains, unique to each vineyard, grow in the slowly bubbling juice, each contributing its own character. It will be interesting to see what the expert report has to say.
UPDATE: This article first appeared in The Weekend Australian Magazine, June 19, 2010. At the meeting the following week, council once again rejected the brewery proposal.

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