a winemaker punching down the cap during fermentation of red grapes


Definition: In winemaking, “cap” refers to the collection of grape skins, stems, and seeds that rise to the surface during fermentation. This cap must be regularly submerged into the wine to ensure proper fermentation.

Context and Usage: The cap can trap heat and prevent carbon dioxide from escaping, slowing fermentation. The cap is “punched down” using various methods to avoid this. The winemaker can extract color, tannins, flavor, and aromas from the grape solids by breaking up the layer of skins, stems, and seeds that form at the surface of fermenting red wine. This process is also known as “pigeage.” Today, tools like a plate or a fork on a pole are commonly used, though, in high-volume wineries, it’s common to find a sizeable pump-over system in use.

Additional Information: Punching down the cap is essential to maintaining the correct fermentation temperature and allowing gases to escape. This practice also helps extract color, tannins, and flavor compounds from the grape skins into the wine.

Example: In a small winery, the winemaker might punch down the cap several times daily using a specialized tool, ensuring the wine ferments evenly and develops its intended characteristics.