What is the primary byproduct of yeast fermentation that contributes to the flavor of wine?

Ethanol is the primary byproduct of yeast fermentation that plays a significant role in the flavor and character of wine. During the fermentation process, yeast converts sugars present in the grape juice into ethanol and carbon dioxide. The concentration of ethanol not only affects the alcohol content of the wine but also contributes to the overall taste profile.

As a significant component of wine, ethanol enhances the perception of body and mouthfeel, influences the aromatic properties, and interacts with other compounds in the wine to contribute to its complexity. While other byproducts of fermentation, such as carbon dioxide, acetic acid, and glycerol, can also impact flavor, it is ethanol that is chiefly recognized for defining the alcoholic strength and foundational taste characteristics of the wine.