What are the primary volatile aroma compounds produced by Brettanomyces and how can their formation be controlled?

Brettanomyces (often shortened to 'Brett') is a spoilage yeast that can produce several volatile aroma compounds, primarily 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG), which can negatively impact wine quality. These compounds are responsible for aromas described as barnyard, horse sweat, medicinal, band-aid, or smoky. The specific aroma profile depends on the concentration and ratio of 4-EP and 4-EG. 4-EP is typically associated with more barnyard-like aromas, while 4-EG contributes smoky and spicy notes. Brettanomyces produces these volatile phenols throug....