What is the primary role of yeast in beer brewing?

The primary role of yeast in beer brewing is to ferment sugars. During the fermentation process, yeast consumes the sugars present in the wort (a mixture of water, malt, and hops) and converts them into alcohol and carbon dioxide. This conversion not only produces the alcohol content in beer but also contributes to the development of flavors and aromas that characterize different beer styles. Yeast can also influence the mouthfeel and overall balance of the beer, making it a critical component in the brewing process.

The other roles mentioned, such as adding color or enhancing flavors, are primarily achieved through the choice of malt or hops used in the brewing process, not by yeast itself. While yeast does produce carbonation as a byproduct of fermentation, the main function remains the fermentation of sugars to create alcohol. Thus, the emphasis on yeast's primary role rightly centers on its ability to ferment sugars, making it an indispensable element in beer brewing.