What is a key difference in the fermentation of red wines compared to white wines?

Red wines are characterized by the inclusion of grape skins during fermentation, which is a key differentiating factor from white wines. The skins of red grapes contain anthocyanins, which are responsible for the color of red wine, as well as tannins, which contribute to the wine's structure and aging potential. During fermentation, the skins impart not only color but also flavors and tannins into the juice, enhancing the complexity and richness of the final wine.

In contrast, white wines are typically made by pressing the grapes and fermenting the juice without the skins, which allows for a lighter color and different flavor profile. The absence of skins in white wine production is crucial as it influences the clarity, flavor, and overall characteristics of the wine. Thus, the practice of keeping the skins in the fermentation vessel for red wines is essential to the production process, making this option the key difference between red and white wine fermentation.