Brett may be caused by new oak

  • Wednesday 21 November 2007

New oak barrels may be responsible for brettanomyces, consultant winemaker Matt Thomson has said.

Thomson, who consults for New Zealand's Saint Clair winery as well as Italian and French producers, was speaking about the yeast infection that can strip a wine of its fruit and create aromas described as ‘mousey’ or ‘horsey’, at a seminar on brettanomyces hosted by Liberty Wines.

He said, ‘Although some scientists don’t agree, many winemakers – myself included – believe that the source of brettanomyces lies in new barrels coming into a winery.’

Once a winery is infected by the rogue yeast, it can be extremely difficult to get rid of as the risk of cross-contamination is high and preventative measures can limit the range of vinification techniques used by winemakers.

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.’

He speculated that this increased demand for new oak may have led to the harvesting of wood from infected sources – and that the toasting process involved in creating new barrels may produce compounds that may be a source of food for the Brettanomyces cells.

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