It happens that you read or hear about "continuous pumping over" or punching down during winemaking as a demanding practice and a guarantee of quality, regarding red wines. But what is it, exactly?
The need for continuous pumping over of the wine arises from the fact that a few days after the start of fermentation the pomace (i.e. the solid parts such as skins, seeds and possibly stalks) begin to float on the must. This creates a solid part which is called the "hat". In constant contact with the air the cap would sour, becoming prey to oxidizing bacteria. The hat must therefore be "broken" and the solid part brought back into suspension.
REPLACEMENTS IN WINE
The pumping overs are mechanical actions whereby part of the must is taken with a pump from the lower part of the vat and through an external pipe it is made to rain down from above (in truth there is also another way: introducing inert gas into the vat to regular intervals).
Pumping overs are generally carried out a couple of times a day .
In addition to preventing oxidation, there are also other advantages derived from pumping over:
- It favors the release of coloring substances from the skins.
- The yeasts are distributed evenly and receive oxygen, reinvigorating themselves.
- The temperature is reduced , albeit to a limited extent.
- The general outcome of continuous pumping over is the activation of fermentation.
- Also read our complete guide to winemaking
MILLATIONS IN WINE
Ancestors of pumping over are punching down, once manual with lots of shifts, that is, mixing, with branched sticks, the must contained in small open wooden vats. Today punching down is possible in steel fermenters equipped with automatic stirrers.
Finally, in the production of important wines , délestage (emptying) is also used: all the liquid part is removed , leaving only the solid part inside the tank, to then be reintroduced. In this way you are sure that you have completely broken the cap and that you have completely reactivated the fermentation.