An Intro to Maceration Management: Pump Overs & Punch Downs

Assistant Winemaker Bill Anton punches down the cap with a punch down tool.

“Maceration management is the most complex and critical stage of red winemaking,” City Winery winemaker explains. He continues:

“The best way to manage maceration is to adapt yourself every day for every tank and to see each tank as its own person or batch. Every day, every tank is behaving differently. Not coming in for one day would cause me to lose sight of what’s going on.”

Maceration is the process through which the solid part of the must — including the grape skin, seeds and pulp — comes in contact with the liquid content — the grape juice and young wine — to impart the desired color and amounts of tannins and aromas to the juice.

During this stage of winemaking, it is important to facilitate the right amount of solid and liquid contact, so that maceration is optimized.

There’s only one pesky thing that gets in the way: carbon dioxide. As sugars in the juice are converted to alcohol during fermentation, carbon dioxide is created as a byproduct. The gas rises to the top of the vessel, pushing the solid materials — including grapes, seeds and pulp — to the top of the container, creating a solid block of fruit, known as the cap (as pictured above).

Right: Assistant Winemaker Bill Anton uses his full body force to punch down.
Left: Carbon dioxide escapes through the cap as Winemaker David Lecomte punches down.

The cap has a tendency to dry out if it’s not redistributed into the juice, causing maceration to slow to a halt.

Lecomte says that one tank produces 20-22 times its volume in carbon dioxide during fermentation. At City Winery, we use a carbon dioxide extractor, which constantly pulls CO2 out of the tanks and into the winery. To keep the winery ventilated, we keep the dock door open when the extractor is on.

The wines are constantly changing during this period. With such rapid change in the wine, maceration management takes over during this time of year, pacing the staff’s work flow, as pumping over and punching down needs are high.

3 Ways to Manage Maceration

There are three methods for maceration management: punching down, pumping over and rack & return. Lecomte explained each method thoroughly — here’s an overview:

1. Punching Down: The first way to integrate the cap back into the juice is punching down, a method very common in the Burgundy and Rhône wine regions of France. Punching down is when the cap is manually or mechanically pushed back into the juice from the top. Feet, a punch down tool or a hydraulic piston can be used to punch down. At City Winery, we use a punch down tool (as pictured above).

Punching down can only be completed when an open-top tank is being used. The team places a wooden beam across the lip of the tank and gets to work with the punch down tool, using the beam to step on for balance.

During the beginning phase of maceration, so much carbon dioxide is produced that the cap is strong enough to walk on. We wouldn’t recommend trying that, though, because one slip into the juice could be fatal. Death is highly likely if a person falls into a fermenting tank of wine, because the carbon dioxide is so strong that it is impossible to breath, even in the case that you get your head above the cap quickly.

Assistant Winemaker Bill Anton pumps over wine.

2. Pumping Over: Pumping over is when liquid from the bottom of the tank is transferred to the top of the tank to submerge the cap. Generally, this is done through two methods. In the first method, a hose is connected to a spout at the bottom of the tank and pushes wine through a pump and into a second hose that sprays the wine onto the cap (as pictured above).

In the other method of pumping over, the wine is emptied through the bottom spout into a tub, so that it can aerate. As the tank is emptied, a hose connecting to a pump siphons the juice through to a second hose that sprays it onto the cap. In both instances, the same tools are used, but the only differing step is aeration.

If a wine has slightly reduced, the team will first aerate it before pumping over.

When a wine has reduced — which is detected by the smell of sulfur, rotten eggs, onion or boiled cauliflower, depending on the level of reduction — it needs air. In this case, the team will use the air method (as pictured above) when pumping over.

3. Rack & Return: The last type of maceration management is called “rack & return” and it’s a new method that’s starting to appear in the Bordeaux wine region of France. This method is uncommon, though, as it requires the availability of two tanks. Racking is the process of carefully moving wine from one place to another. In this case, half of the wine in a tank is moved to another tank and then returned to the original tank at a high velocity using a pump at full speed, causing the cap to break up.

With pumping over, wine can only be pumped as fast as it is flowing out of the tank — that way, it’s replacing the tank at the same rate. For example, today we’re using a pump at 40% its capacity — it can pump up to 120-gallon per minute. This is all based on the flow of the wine from the tank.

With the rack & return method, though, all of the juice in the second tank can be pumped at full speed into the original tank, overwhelming and breaking up the cap. This method enables a winemaker to extract the most character from the solids in the must and can be employed when pumping over isn’t enough. This method, though, would very rarely be used at the end of fermentation, because too much extraction would occur, pushing the wine into a bitter, aggressive state.

Variables to Consider in Maceration Management

Maceration takes about 2-3 weeks, and it’s a balance — the winemaker wants to extract as much potential from the solid materials in the wine as possible. If he extracts for too long, though, the wine can become bitter, harsh or too aggressive, because it begins to extract tannins from the seed, and not just the skin.

If he extracts for too little time, though, the wine may not be as complex as it could be, generally producing a more fruit-forward, than complex, wine.

In general, pumping over and punching down occurs once or twice per day, but can take place as much as 3-4 times per day at the peak of fermentation.

So, how does a winemaker know when he should pump over or punch down? Or whether he should use air to oxygenate the wine during the pump over process? Lecomte says there are a number of variables, of which these are just a few for starters:

  • Whether or not the juice has started fermenting
  • What the pH level is
  • What the Brix reading is
  • Whether the wine will have difficulty finishing the fermentation process
  • Whether another shipment of grapes is to arrive and needs to be placed in the tank
  • What the winery’s pump capacity is
  • What the winery’s cooling capacity is
  • Whether the tank is an open or closed-top tank
  • What the temperature of the juice is
  • How many Brix have been lost within 24 hours
  • What other wines in the winery are higher priority and must be tended to first
  • How much time and how many staffers the winery has available

Lecomte explained that while two wines can have the same Brix reading, for example, they may be behaving completely differently, so the day-to-day maceration management of each will be different. All of the variables listed above — and more — must be taken into account when dealing with each tank.

Maceration is a complicated process, and this post is merely an introduction to how the City Winery manages this phase of winemaking. Let us know if you have any particular questions in the comments below!