Winery technology and vinification: Pumping over or remontage
”Pumping over” (called remontage in French) is a technology used in the winery to increase extraction. The winemaker performs it by emptying fermenting must from the bottom of a tank and then pumping it to the top of the tank. A tube is attached to a must pump and the must is sprayed over the top of the must in the same tank. This is done in order to soak the floating ”cap” (chapeau). The cap is mostly grape skins that have floated to the top of the must due to the release of carbon dioxide. It is a semi-solid layer that needs to be kept wet.
By doing the pumping over (remontage) the winemaker increases the extraction of tannins and colours from the skins. The pumping over can be done by letting the must flow out into a trough and then pump from there. This gives added oxygenation. Alternatively the tube is attached directly to the tank. The must is then sprayed over the cap manually or with a spraying device.
A similar, but different, vinification technique is ”rack and return” (called delestage in French). In that case the liquid part of the must is emptied from the fermentation tank and then pumped back over the solid parts that remained in the tank. This gives an even stronger extraction of anthocyans and polyphenols.