How does primary fermentation primarily affect beer?

Primary fermentation primarily converts sugars into alcohol, which is a fundamental process in beer production. During this stage, yeast metabolizes the fermentable sugars extracted from malt, producing ethanol and carbon dioxide as byproducts. This transformation is essential, as the alcohol content is one of the defining characteristics of beer.

The role of primary fermentation goes beyond just alcohol production; it also influences the beer's flavor profile and contributes to esters and phenols, which add complexity and character. However, the core function of this fermentation phase remains the conversion of sugars into alcohol, making it crucial for developing the beverage's overall alcoholic strength.

While carbonation is primarily a result of CO2 produced during fermentation, it is not the main effect; it typically occurs during the secondary fermentation or packaging stages. Bitterness is primarily derived from hops and occurs earlier in the brewing process, while color changes are influenced by the choice of malts rather than the fermentation itself. Thus, the most accurate description of primary fermentation's primary impact on beer is its conversion of sugars into alcohol.