High levels of which components contribute to the viscosity of wine?

The viscosity of wine is influenced primarily by the concentration of sugar and alcohol. Both of these components are viscous in nature. Sugar, particularly residual sugar, creates a thicker mouthfeel as it increases the overall density of the wine. Alcohol contributes to viscosity as well; as its concentration rises, it can give the wine a richer and more viscous texture. This is why sweeter wines or those with higher alcohol content feel fuller and thicker on the palate.

While phenols and tannins do contribute to the texture and mouthfeel of wine, they primarily affect the astringency and flavor profile rather than viscosity in the way that sugar and alcohol do. Acids and esters pertain more to the sharpness and aromatic quality of wine, and water and minerals can influence the overall balance and flavor but do not significantly contribute to viscosity. Thus, the correct identification of sugar and alcohol as the key components of viscosity provides a clearer understanding of how these elements affect the wine's texture and mouthfeel.