Winemakers are increasingly returning to the past to improve their wines, and there are few places that is more apparent than in the increasing use of larger-than-standard oak barrels for aging and large oak vats for fermentation.

Winemakers who love using barrel formats larger than 60 gallons say they offer softer tannins and smoother mouthfeel than steel tanks. They also find that wood fermentation vats add the advantages of oak without excessive “oakiness.”

Meanwhile, large oak vessels are irresistible draws in wineries, even if they are expensive to buy and challenging to maintain.

Perhaps no large tanks can match the visual impact of the 56 large Taransaud fermentors that dominate the elegant To Kalon Cellar at Robert Mondavi Winery in Oakville, Calif. Winemaker Genevieve Janssens finds them the perfect match for the winery’s To Kalon Cabernet Sauvignon.

“We ferment our best blocks of Cabernet Sauvignon from the To Kalon Vineyard in the vats,” Janssens says. “To Kalon Cabernet has lot of structure and austerity. It’s big in tannins and polyphenols. The fermentation in large oak tanks softens the wine and makes the fruit stand out.”

The vats don’t impart oak flavor, however, as the ratio of must to surface area is too large. The oak vats have a capacity of 16 tons and are nearly 11 feet tall, almost 10 feet in diameter at their widest point and 8.75 feet across at the top. Coopers from Tonnellerie Taransaud in France assembled them in June 2000.

Janssens admits that maintenance of the tanks is almost a full-time job. She follows the strict protocols provided by Taransaud and contracts with the cooper to maintain the tanks. Every August they check both the physical soundness and the microbiology of the tanks.

Janssens has also been using the tanks for Pinot Noir for four or five years, starting some tanks with Pinot Noir before fermenting Cabernet.

The tanks are obviously expensive, but Janssens says that they’re a good investment for the quality received. She expects to use them for 30-40 years.

Aesthetic appeal
Jeff Gaffner also makes wine in dramatic oak tanks, his being 5- to 6-ton Radoux fermentors at the impressive new Ram’s Gate Winery designed by architect Howard Backen in Carneros near Sonoma, Calif. “The tanks are aesthetically beautiful married to the building.”

Gaffner admits the idea of the oak tanks first came up in the context of visual appeal. However, he had fermented wine in wood previously and decided to do some research. “I realized this could be a real cool opportunity. It’s a really new ingredient I could use in my winemaking.”

He hasn’t had a lot of experience with the new vats yet, but already he’s noticed fermentation proceeds differently. “The temperature changes are more subtle in oak tanks than in stainless steel,” for one thing. He gets two or three turns for wine batches during a vintage.

They also are more challenging to keep clean. “They were brand new at Ram’s Gate, so they were clean to start with. Our job is to keep them that way.

“We believe that the oak will stay clean if you empty them out and dry them well,” he says, although he knows that some wineries keep them wet. He’s using the vats for fermentation, not aging, so he is not looking to get oak flavors from them.

“There’s a lot of work,” Gaffner says. “I wouldn’t want them in a large winery. Bad things can happen.”

For Sangiovese and Zinfandel
Consulting winemaker Chris Dearden had a lot of experience with larger formats when he worked at St. Helena, Calif.-based Benessere Vineyards, which specializes in wines made from Italian varieties.

While there, he used 54-hectoliter (1,400-gallon or 5-ton) tanks for both fermentation and storage. They were truncated cones, and the tops had large manholes that could be sealed, so Dearden could use them open or closed. That also made them suitable for storage if they were topped up. “They were integral to producing Sangiovese, Pinot Noir or Zinfandel. They seem to react well.” He adds that they were excellent for helping stabilize color in varieties that had weak color, like Sangiovese.

He also found the oak tanks excellent for aging and concentrating the wines but he wasn’t after oak flavor. “Big wood isn’t about oak flavors.”

Over time, they lost their effectiveness. He found 10 to 15 years was a useful life before bacteria took over. He says Italian winemakers only use them for five to seven years.

Dearden admits, “They can be dangerous. There’s a lot of risk. They’re like a Ferrari: Great performance, but you need to treat them with a lot of care.”

He stored them empty. After using, he cleaned them out scrupulously of lees and tartrates, dried them thoroughly, kept them full of SO₂ and treated them with ozone before harvest.

“We didn’t have TCA and didn’t use chlorine in the winery,” he says, adding that ETS Laboratories has cheap tests for TCA. He kept Brettanomyces at bay with careful sanitation.

Oak tanks at Vineyard 29
At boutique producer Vineyard 29 in St. Helena, Calif., winemaker Keith Emerson uses seven 75-hectoliter Radoux fermentors for the winery’s estate Cabernet. In the eight years he’s been at the winery, he has bought two new ones and sold two old ones each year to renew his stock.

The vats contain internal stainless steel screens to exclude seeds and stems. They also have heat-transfer plates with hot and cold glycol to maintain temperature during fermentation.

Emerson says that the oak fermentors round out the intensity and feel of the tannins. “They give a rounder texture than stainless steel,” he says.

He also finds they ferment wines cooler, leading to a long extraction: 30 days and sometime longer. “Even after all that time in a new tank, the wines aren’t oaky,” he says.

On the other hand, he admits that they’re not the easiest equipment to maintain. Emerson treats them with SO₂ and hot water with citric acid monthly. He also puts an ultraviolet lamp in them a few times a year—just in case. “I found that the UV lamps we use in the caves fit in the door.”

Emerson also has stainless steel and concrete tanks, and he’s comparing the results long term.

In addition to fermenting Cabernet in oak, Emerson also ages all the winery’s estate Zinfandel in 500-liter oak barrels. “The wine has softer tannins. The tanks match Zin well.” He ages wine for 20 months, then knocks out one end, cleans them and uses them for fermentation of Pinot Noir.

Jean Hoefliger, the winemaker-general manager of Alpha Omega Winery, also in St. Helena, Calif., is a native of Switzerland, where he had experience with large oak formats—some of them dating from the 1700s and still in use.

When he came to the U.S., he worked at Newton Vineyards, which aged wine in 1,000-gallon oak tanks. They were 11 to 15 years old, so they didn’t contribute oak flavor, but mostly micro-oxidation. He replaced half of them with stainless steel and switched to replacing the oak tanks after six years.

In 2001, he started fermenting red wines in standard-size barrels; the same barrels can be used for aging, but he does not use the large vats this way. They’re also expensive.

Wood is a good insulator
Gilles Nicault of Long Shadows Winery in Walla Walla, Wash., uses big tanks and barrels as requested by the winery’s winemaking partners. Nicault explains, “Michel Rolland has asked me to use the 55hL Radoux wood tanks for his Pedestal program at Long Shadows Vintners to ferment his Merlot. The wood being a good insulator, it keeps the temperature more constant, especially toward the end of fermentation, and contributes to a healthy fermentation.

“Plus,” Nicault continues, “the wood provides tannins and oxygen. Wood tannins will help the structure and texture of the wine but will also protect the grape tannins from oxidizing. A higher concentration of grape tannins and oxygen will help retain more anthocyanins in the wine and will create a wine with more intensity and richness.”

For making Pirouette wines at Long Shadows, winemaker-partner Philippe Melka uses the 400-liter Baron fermentors placed on the OXO wheelbase in order to ferment the Cabernet Sauvignon. The idea of using oak barrels for fermentation is the same as for the wood vats, but the ratio of oak to must will be dramatically increased. “The wines usually show an incredible depth with a lot of dark character,”
Nicault says.

To maintain them, Long Shadows uses ozonated water once a month to rehydrate the tanks and barrels. “We keep the tanks open for a good air flow and sulfur the barrels. We have had no problem keeping them fresh,” Nicault says.

Joel Aiken, who’s now a consultant as well as producing his own brand, worked for Beaulieu Vineyard in Rutherford, Calif., for many years, the last several as chief winemaker. His experience included using large redwood tanks for holding wines before bottling, but never for long periods. Some had been in use since 1947, while the newest were bought in 1970. “They had no impact on the wine,” he says.

Toward the end of his tenure at BV, Aiken acquired two 1,500-gallon French oak tanks for fermentation. “They added the complexity of oak compared to stainless steel. “You got more mocha and softening of the tannins from oaky to complex.”

Aiken left the vats empty after fermentation and used SO₂ and plenty of air to keep them sweet. He then filled them with water in time to completely hydrate before the next harvest.

Puncheons and hogsheads
While some wineries are using large oak tanks for fermentation, more are using oversized barrels, often called puncheons and hogsheads for varying sizes. Schug Carneros Estate Winery in Sonoma, Calif., uses 130- to 160-gallon puncheons from Radoux and 320- to 360-gallon barrels—as well as some barrels holding 640 gallons. Schug also has large oval profile tanks that hold 350 to 1,100 gallons and are used for aging reds and whites. The winery’s founder Walter Schug learned winemaking in his native Germany, and much of the wood is from Germany.

Schug winemaker Mike Cox uses the larger formats to ferment Sonoma Coast Chardonnay and Sauvignon Blanc. “It advances the nature of the wine,” he says. “The fruit is more forward, and there’s some softening. It’s also more yeasty in character.”

He ferments the wine in stainless steel, where it’s easier to control temperature, then finishes it in the large tanks. Cox also uses ovals for reds, primarily for malolactic fermentation. “We toss in a bag of oak chips to fix color in lighter wines,” he says, adding that the tanks are old enough that there’s little impact from the wood.

Cox inoculates with malolactic bacteria at the start of the season and says it’s enough for repeated uses. He keeps some lighter Sonoma Coast Pinot Noir in ovals year-round—both for aging and to maintain the barrels. His Carneros Pinot goes to barrels, however.

Cox admits that all the big oak requires a lot of maintenance. He likes using ozone to sanitize them and figures they’re good for 30 years.

Jean Hoefliger of Alpha Omega, in addition to his experience with large oak fermenting tanks, ages Chardonnay and Syrah in 300-gallon barrels to limit the new oak character. He believes the larger vessels better integrate the wood and wine, while they don’t bring as much fatness or creaminess as small barrels.

He also likes the lower level of oxidation through the wood in the larger tanks and finds that roasted hazelnut aromas develop.

Hoefliger finds the biggest problem with the larger barrels is logistics. “Stacking and storage are a huge issue,” he says. They’re hard to handle and expensive. He uses them for three years for Alpha Omega Chardonnay, filling them with press wine during the third year.

Dearden, who at one time sold imported Gamba barrels, agrees that large barrels are unwieldy. “They’re too heavy for the normal person to deal with,” he says.

Gaffner of Ram’s Gate uses large-format barrels as well as wood fermentation tanks. “I love Syrah aged in puncheons and hogsheads,” he says. “It integrates the wood more slowly.” He adds that he never uses the larger barrels for Napa Valley Cabernet.

Gaffner says he first used the large barrels for Chardonnay and Pinot Noir at  Saxon Brown, then aged Syrah in them.

Winemaker Ashley Hepworth at Joseph Phelps Vineyards in St. Helena, Calif., has some 500-liter barrels she uses to age Sauvignon Blanc and Viognier. “The oak is a little more elegant and less pronounced,” she says. “I really like their impact.” She buys them from Tonnellerie Ermitage, Tonnellerie Francois Freres, Dargaud Jaegle, Damy Cooperage and Billon.

She cleans the barrels with ozone and uses them for six to eight months for white wines and 18 months for reds.

When the barrels are empty, Hepworth washes them at least every two months with ozone and water, and she steams them once a year.

Winemakers are once again turning to old techniques for inspiration, and many find that large barrels and oak fermentation tanks provide the textural benefits of smaller oak barrels—but without the oakiness that some consumers reject. They are expensive and difficult to maintain, but many winemakers find their benefits are worth the trouble and expense.