High levels of sugar and alcohol in wine affect what key characteristic?

High levels of sugar and alcohol in wine significantly influence viscosity, which refers to the thickness or weight of the liquid. When sugar content increases, it contributes to a greater density; similarly, high alcohol levels increase the body of the wine, leading to a more viscous mouthfeel. This is commonly observed in dessert wines, for example, which tend to have a higher sugar content and a syrupy, rich texture that coats the palate.

Understanding viscosity is crucial for distinguishing between different styles of wine and assessing their overall body and mouthfeel. While color, aroma, and taste are all important aspects of wine, it is the physical characteristic of viscosity that is most directly impacted by the concentrations of sugar and alcohol. Viscosity can often be discerned visually by the "legs" or "tears" that form on the inside of a glass when wine is swirled, revealing its richness and texture.