What is the primary flavor profile of a sour beer?

A sour beer is characterized primarily by its tart and acidic flavor profile. This distinct taste comes from specific fermentation processes that involve wild yeast strains and bacteria, such as Lactobacillus and Brettanomyces. These microorganisms produce lactic acid and other compounds during fermentation, which contributes to the beer's sourness.

The tartness in sour beers can vary widely, from mildly tart to sharply sour, depending on the brewing methods and ingredients used. Sour beers also often have a complex interplay of flavors that might include hints of fruit, but the defining feature that sets them apart from other beer styles is that pronounced sourness and acidity.

While it’s true that sour beers can have a variety of other flavor notes, such as fruity elements from the addition of fruits or the fermentation process, the fundamental characteristic remains the tartness. Therefore, when identifying the primary flavor profile of sour beer, the emphasis on tart and acidic flavors is what makes this style unique.