What factor is primarily affected by phenolic compounds in wine?

Phenolic compounds in wine play a crucial role in determining both the color and aroma, making this the correct response. Phenolic compounds include a variety of substances such as tannins and anthocyanins, which are found in grape skins, seeds, and stems.

In red wines, for instance, anthocyanins are the pigments responsible for the wine's color; they react differently depending on factors like pH and the presence of other compounds during fermentation and aging. Additionally, tannins contribute to the mouthfeel of the wine and can influence aroma by interacting with other aromatic compounds. These components not only impact the aesthetics of the wine but also its sensory characteristics, such as flavor depth and complexity.

The other options do not directly relate to the primary role of phenolic compounds. Sugar content is influenced by the grapes' ripeness and fermentation processes but is not significantly altered by phenolic compounds. Similarly, alcohol content is determined by the fermentation process where sugars are converted into alcohol and is not directly affected by phenolics. Carbonation levels primarily relate to the presence of gases in the wine, which are not a direct result of phenolic compounds either. Thus, while phenolic compounds are integral to a wine’s profile, their influence is most evidently