New oak barrels may be responsible for brettanomyces, consultant winemaker Matt Thomson tells Decanter.
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 flavor, and create aromas described as “mousey” or “horsey.”
Although some scientists don’t agree, many winemakers — myself included — believe that the source of brettanomyces lies in new barrels coming into a winery,” he said.
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 due to new wine styles that are low in acidity and relatively high in residual sugar, and also due to increased demand for new oak barrels.”
Thomson 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 serve as a source of food for the brettanomyces cells.