What are the bitter compounds found in grape skins called?

The correct answer is tannins, which are the bitter compounds that are predominantly found in grape skins. Tannins are a type of polyphenol that contribute not only to the bitterness and astringency of wine but also play a significant role in its structure and aging potential. These compounds are extracted from the grape skins, seeds, and stems during the winemaking process, especially in red wines, which undergo longer maceration periods.

Tannins are critical in balancing the sweetness and acidity of wine and can enhance the perception of overall mouthfeel. They also have antioxidant properties, which can be beneficial for health. Their presence can vary greatly among different grape varieties and can impact the flavor profile of the resulting wine.

While flavonoids are also a class of compounds related to color and taste in various plants, they are not specifically identified as the bitter components in grape skins. Phenolics is a broader term that encompasses tannins and other compounds, while anthocyanins specifically refer to the pigments that provide red, blue, and purple hues in wine and are not associated with bitterness.