This month we would like to take a closer look at some cap management techniques. But first, what exactly is a “cap” and why does it need to be managed?
Many people know that red wines acquire their colour from the grape skins which are left in contact with the fermenting grape juice, but because of carbon dioxide, most grape skins will be pushed to the top of a tank, which then creates a “cap”. This only leaves a small portion of the juice in contact with the skins and therefore limits the extraction of colour and tannin and flavour occurring throughout the tank. Consequently, it is then up to the winemaking team to “manage” this cap, and the extraction process.
This can be done in several ways, but traditionally punch-down is used. Punch-downs, which are known as “pigeage” in French, are used on small lots of grapes in open top fermenters. In this process the cap is manually broken and mixed with the fermenting grape juice by using a plunger to submerge the cap. This allows the skins to infuse with the fermenting must while letting heat escape. This method releases tannins, colour and flavour from the grape skins and is performed one to three times a day depending on the level of extraction required. If you are having trouble picturing this process, think of a coffee plunger and the process that is required to submerge the plunger.
Another extraction method commonly used in cellars are pump-overs, or “remontage” in French. This extraction method is performed on larger tanks where punch-downs are not a possibility. In this case, the juice is removed from the bottom of the tank and then pumped over the cap to allow for extraction. Either a sprinkler or hose can be used to wet the cap, which has more of a percolation than breaking effect. Overall, this is a gentler process of extraction than a punch-down. Generally, this method will also be performed up to three times per day depending on the desired extraction.
The final method used for extraction would be a rack-and-return – or “délestage”. This method is capped to two times during the fermentation cycle. Here the red wine must is separated from the solids (grape skins and seeds) and then returned to the fermentation vessel to re-soak the solids. This process oxygenates and aerates the must and softens astringent tannins through oxidation. In this example, the fermenting must is drained (racked) from the tank and pumped to another tank until there is no more juice left in the original tank with the skins. The juice in the new tank is then returned and splashed over the top of the skins of the original tank to extract the colour and tannin.
Whilst there are other, niche methodologies, that just about covers most of it. The next time you hear a winemaker talking about “wetting the cap”, you will know exactly what they are on about.