Which ingredient primarily determines the style and flavor complexity of a beer?

Malt is the key ingredient that primarily determines the style and flavor complexity of a beer. Malted grains, usually barley, provide the fermentable sugars necessary for yeast to produce alcohol. Additionally, malt contributes a wide range of flavors, aromas, and colors to the beer, depending on the type of malt used, how it was processed, and the specific style being brewed.

For instance, lighter malts create crisp, clean flavors and pale ales, while darker malts can impart rich, roasted flavors typical of stouts and porters. The variety of malt used and the Maillard reaction that occurs during kilning and roasting contributes to the complexity and character of the beer. This foundational role of malt in establishing the base flavor profile sets the stage for other ingredients like hops and yeast to build upon, but malt remains the primary driver of the beer's style and overall taste.