The barnyard aroma in wine is associated with which?

• A. Cork taint
• B. Brett
• C. Malolactic fermentation
• D. Sulfur

Answer: (B)

The barnyard aroma in wine comes from Brettanomyces, a wild yeast that can colonize wine and barrel environments. When present, Brett produces volatile phenols such as 4-ethylphenol and 4-ethylguaiacol, giving smells reminiscent of a horse stall, barn, leather, or medicinal notes. At low levels, some winemakers tolerate a hint for complexity, but at higher levels it dominates the aroma and is considered a fault. Cork taint is caused by the compound TCA and smells musty, like damp cardboard; malolactic fermentation mainly adds buttery or creamy notes from diacetyl, not barnyard; sulfur compounds can create rotten-egg or burnt-match aromas, not barnyard. So Brettanomyces is the best fit for the barnyard scent.