Punch-Downs and Pump-Overs: Unlocking Red Wine Color

For those that have been following along on our recent wine journey, over the past couple weeks we’ve discussed vineyard activity, timing of harvest, and grape processing at the winery. The last blog focused a bit on sorting, crushing, and pressing, where the distinction between still white and red winemaking bifurcates. To recap, for white wine, grapes are pressed before fermentation to retain their acidity, aromas, and flavors without extracting undesired effects from the skins, pulp, and stems. For red winemaking, pressing occurs after fermentation. What is the distinction here? As we know, the juice (pulp) of a red grape is clear, just like white grapes, so how do we get red wine to take on red color before the must (grape juice) is pressed? 

This is a very common question, and one that can be answered by describing a couple different options the winemaker has at their disposal. Let's talk about these options by introducing the terms punch-downs and pump-overs—woo-hoo! If you have ever spent any time around a winery, I am sure you have heard these terms used. Punch-downs (French term:  Pigéage) are as simple as it sounds. During red winemaking fermentation, CO2 and heat are created as a byproduct of the yeast converting the sugar into alcohol. This CO2 pushes the must cap (grape skins and seeds of fermenting juice) to the top of the fermentation bin or tank, which can also insulate the wine, leading to overheating during fermentation. Because the color (anthocyanin pigments) and many flavor compounds are in the skins, as well as tannins, we want to incorporate the must back into the juice to extract these flavor and color compounds, while also mitigating any heat that may be detrimental during fermentation. 

A device called a punch-down tool is used to push the skins back into the juice (a process called maceration). Depending on what tool(s) are used (whether mechanical or manual), it takes about 3-5 minutes to punch down one tank, longer when the fermentation is first getting started (less juice and a ton of CO2 being produced), and once the fermentation nears completion and there is less CO2 being produced, the punch-downs become much easier and shorter in duration. Punch-downs are fairly gentle on the grapes, and typically their done 2-3 times a day, on average. Some tanks may see more, and some less. Many times, the frequency depends on the varietal, the desired tannin level, and the amount of color extraction and flavors sought. Because punch-downs take a TON of energy and muscle power to execute (unless you’re very fortunate to have mechanical devices), the music listened to is VERY important. High energy music is what works best to get you through a punch-down routine. Perhaps you can ask Lacie to create a playlist for you; she made a solid cellar rat playlist for us this year!

As part of this cap management, an alternative to punch-downs is a process called pump-overs (French term: Remontage). Typically, pump-overs are completed in larger tanks where punching down the skins is virtually impossible. Pump-overs is a term that gets its name from pumping the juice back over the skins in the tank via a pump. Genius, huh? Instead of submerging the skins into the juice using a punch-down tool, a hose is attached to the racking valve (lowest point) of the tank, and the juice is pumped back to the top of the tank and splashing it over the top of the skins. This allows the skins and juice to stay in contact with each other, getting the extraction of color and flavor and tannin compounds that is desired in the wine(s). Using this method also introduces oxygen into the fermentation, keeping the yeast happy and healthy. The pump-over method can also be used on some of the smaller tanks, especially if any whole grape clusters are being used during the fermentation (which makes for a VERY difficult punch-down) or to introduce more oxygen to the fermentation (punch-downs are not as effective in introducing oxygen to the ferment as pump-overs). 

While on the subject of oxygen, or lack thereof, you might have heard the term “reductive” in winemaking. "Reductive wine" can refer to a winemaking style or the resulting wine's aromas. Reductive winemaking intentionally limits a wine's exposure to oxygen to preserve fresh fruit flavors and create a lighter, fruitier style, as seen in some Chardonnays or Chenin Blancs. However, if excessive, this lack of oxygen can lead to "reductive notes," which are undesirable, often sulfurous aromas like rotten eggs, burnt rubber, or onions. 

Ok, again, we’ve covered a lot of ground here. Between this blog and the last one, we’ve caught up with each other at the pressing/fermentation stages for both white and red winemaking and are almost ready to settle into the aging (maturation) stages for both wines. Hopefully by now you’re sensing an appreciation of the many decisions, steps, and processes that are integral in winemaking. Please keep in mind that these blogs touch on some of the higher-level points that occur in the winery. At every step of the way, there are constant adjustments, whether monitoring sugar levels (brix/specific gravity), fermentation temperatures, inert gases being introduced, inoculations during fermentation, pH and titratable acidity (TA) analysis, tasting samples, or the ever-probable problem prevention to ensure production quality. At the end of the day, most wineries, as with many other industries, focus on control and consistency, so you, the consumer can always enjoy that beautiful fermented grape juice. We do hope that these blogs are informative and offer some manageable clarity in our efforts to share what’s going on in the cellars.

Cheers!