In red wines, aside from grape skins and seeds during maceration, what is another source of tannins?

• A. Water used during fermentation.
• B. Oak aging.
• C. Yeast nutrients.
• D. Acid adjustments.

Answer: (B)

Oak aging provides tannins beyond grape skins and seeds. While grape skins and seeds during maceration are the main source of tannins, the wood of oak barrels also contributes tannins as the wine matures in barrel. Oak tannins—like ellagitannins and related compounds—leach into the wine, with the amount depending on whether the oak is new or neutral, the level of toasting, and how long the aging lasts. This wood-derived tannin adds structure and can interact with grape tannins to shape mouthfeel and aging potential. The other options do not supply tannins in a meaningful way.