What compounds can brett or wild yeast produce that affect beer flavor?

Brettanomyces, or "brett," is a type of wild yeast that can significantly influence the flavor profile of beer. One of the key compounds it produces is acetic acid, which can impart a vinegary flavor to the beer, especially when present in higher concentrations. This acidity can enhance the complexity of certain styles, such as sour ales or lambics, contributing to a tartness that many beer enthusiasts appreciate.

Additionally, brett can produce diacetyl, which is often described as having a buttery flavor. While diacetyl is typically considered a flaw in many beer styles, in the right context, it can add a layer of depth and richness to the overall character of the beer.

The combination of acetic acid and diacetyl illustrates how brett can create both intriguing and challenging flavors, allowing brewers to explore unique sensory experiences. This contribution to flavor complexity is a hallmark of beers fermented with brettanomyces, making it a popular choice among craft brewers looking to push the boundaries of traditional styles.