Growing & Winemaking

 

Mixing Tanks With Air

March 2012
 
by Laurie Daniel
 
 
During the most recent harvest at Silver Mountain Vineyards in California’s Santa Cruz Mountains, a compressor pumped air into hoses connected to three evenly spaced valves near the bottom of a 4,000-liter tank of fermenting Pinot Noir. There was a blub, blub, blub sound of air bubbles, then the fermenting juice erupted through the cap of skins at the top of the tank. It was Pulsair technology in action.

Simply put, Pulsair uses large bubbles of compressed air or another gas to mix a tank. The bubble can be introduced from the top of a tank, using a probe, or through other mechanisms at the bottom of the tank. Wineries large and small use it for cap management—as a substitute or adjunct to pumping over or punching down in red wines—or to combine a blend.

Jerold O’Brien, Silver Mountain’s owner, likes Pulsair for several reasons and uses a portable unit on all his reds. “Rising bubbles of air are absolutely the most gentle way to mechanically mix,” says O’Brien, who doesn’t use pumps at his 6,000-case winery. In addition, the process is less labor intensive than his other cap-management regimen, which he calls a “drain over” because the juice is drained from the tank into bins, which are hoisted with a forklift, then drained through a hose over the cap and back into the tank.

Not exactly new 
Pulsair technology was introduced to the wine industry about 25 years ago—the company calls its wine system “pneumatage”—but not much has been written about it. O’Brien and other winemakers who are fans of the process talk about how gentle it is, resulting in wines with supple tannins. Pulsair also allows winemakers to aerate the must, which helps with healthy fermentations, mitigates reduction issues and assists with even distribution of any additions to the tank. Some say that the process even helps blow off excess alcohol.

The technique of using a bubble of air to mix things was developed about 30 years ago by Dick Parks, who was looking for a way to gently mix some salmon eggs. He went on to establish Pulsair Systems Inc., based in Bellevue, Wash., which now has customers in more than 40 countries and a variety of industries.

The oil industry is Pulsair’s biggest customer, but in 1985, Parks got in touch with Doug Gore, now executive vice president for Ste. Michelle Wine Estates, who at that time was red winemaker at Chateau Ste. Michelle in eastern Washington state.  “For some reason, (Parks) got fixated on wine and grapes and (whether Pulsair could) work in a winemaking context,” Gore says.

Gore says he tried Parks’ device, which involved piping the compressed gas under stainless steel discs at the bottom of the tank, on some square, open-top concrete tanks, but it didn’t work properly. “It’s the geometry of it,” Gore says. Pulsair did, however, work “wonderfully well” on some 2- to 3-ton open-top tanks. “That was the start of it,” he says.

Parks, meanwhile, experimented with the technology at some other wineries, refining it as he went along. Gore became winemaker for Ste. Michelle’s Columbia Crest, and when that winery installed some new stainless tanks, he got in touch with Parks. “We’ve used it ever since for mixing our large tanks” during blending, he says. For that purpose, inert gas, usually nitrogen, is used. Gore says that Pulsair is turned on when the tank is 85% to 90% full, and “by the time it’s filled, your tank is mixed.”

Use with portable wand
These days, Columbia Crest, which has annual production of about 2 million cases, also is using Pulsair in some of its red wine fermentations, says current winemaker Juan Muñoz Oca. Pulsair capability is built into 15 of Columbia Crest’s blending tanks, but for fermentations, the winery uses a portable system with a wand that’s inserted through a racking valve. The wand is moved so that a pulse of air is dispensed toward the side of the tank close to the operator, in the middle and on the far side. Muñoz Oca says that one person watches from above the tank to make sure the whole cap gets wet. He uses it only on open-top fermentors; the other tanks, he says, have only a small opening on top, so “you can’t see the burp.”

Pulsair is available in a variety of configurations, says Skip Brunhaver, Pulsair’s head of sales for the western United States. There are several compact, hand-held models suitable for use on bins and small tanks. The next step up, he says, is a wheeled “wine cart” with multiple valves and a controller. A portable unit that’s big enough for a 20-ton tank, he says, costs a little less than $4,500, plus accessories and the cost of any necessary modifications to the tank.

The top of the line is a Pulsair system with permanently installed injection valves and a computer system. Brunhaver says that such a system for eight tanks or more would cost about $5,000 to $6,000 per tank, including the computer.

That’s the type of system that will be installed at Villa San-Juliette’s new winery in Paso Robles, Calif. Winemaker Adam LaZarre plans to use a fixed, computerized system on a variety of tank sizes. “I’m going to outfit everything with Pulsair,” he says. A primary reason is the labor-saving aspect. “I’m a one-person show in the winery,” he says. He also liked the results he saw when he worked with the technology at Monterey Wine Co., a custom-crush facility in King City, Calif.

LaZarre says he compared some Pulsair lots with wines that had been put through pump overs. He thought that Pulsair provided better tannin management because extraction could be more carefully controlled. The system he is installing can be switched between using compressed air and inert gas, so he also plans to use it for blending and making additions to tanks. “I’m going to use it as often as possible,” he says.

Automated versions save labor
The labor-saving aspect can be huge with the automated systems: You just program how often and for how long you want the air pulses. Brunhaver described a large winery, which he wouldn’t identify, that installed a Pulsair system in 40 tanks. The winery was able to cut 11 workers from each of two shifts.

But for many wineries, the main reason for using it is the gent leness of the process.

That’s why Luisa Ponzi, winemaker at Ponzi Cellars in Beaverton, Ore., likes it. Although she doesn’t use Pulsair every year, she employs it for vintages “where that use of air is important (because of reduction issues), or I want to be more gentle” because the grape clusters are fragile. She also uses it for mixing additions into her white wines. “It’s really a great tool,” she says.

However, she notes that it’s possible to overuse it. Too much can strip color and aromatics, she says. “There’s a learning curve at first.”

Brunhaver acknowledges that overuse of Pulsair can be a problem. If you run it for too long, he says, “you make mush out of the wine.”

Brunhaver also says that the process, used properly, provides more uniform extraction and eliminates hot spots in the fermentation tank.

Winemaker Neil Collins, for one, hasn’t seen much of a downside. Although Collins, winemaker for Paso Robles, Calif.-based Tablas Creek Vineyard, says he was a skeptic at first, he now sees Pulsair as a good tool. “It seems to be gentle and effective. We’ve seen absolutely no detriment,” he says. “Wines come out soft and supple.”

Videos of a small Pulsair unit being used for winemaking are posted on pulsair.com and pneumatage.com.

 
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