What effect does tannin have on the taste of wine?

Tannin is a naturally occurring polyphenolic compound found in grape skins, seeds, and stems, as well as in oak barrels. One of its key characteristics is its ability to create a mouth-drying or astringent sensation, which is often described as similar to the feeling one gets from drinking strong black tea. This astringency comes from tannins binding with proteins in the saliva and in the tissues of the mouth, which leads to that drying feeling.

Tannin plays a significant role in the structure and complexity of the wine, contributing to its overall mouthfeel and finish. It balances out sweetness from the fruit, providing a counterpoint that can make the wine more enjoyable, especially in red wines where tannins are more pronounced. This characteristic of tannins is particularly important in red wines, where they help in aging potential, allowing wines to develop and integrate flavors over time.

Other choices do not accurately describe the effect of tannin on wine's taste. While tannins can interact with other components of wine, their main effect is the astringent mouthfeel rather than sweetness, fruitiness, or reducing acidity.