For the sake of a certain style, more and more winemakers are taking two of the most laborious parts of cellar operations— managing red fermentations and barrel work—and combining them.

Barrel fermentation is a winemaking method that’s growing in popularity for imparting silky tannins and a lush roundness to red wines, especially Bordeaux varieties. However, those who have made a commitment to the method say the added labor and lack of fermentation controls make it a process not suited for everyone.

There are essentially two ways to barrel ferment. One is to pop the head off a barrel, fill it with must and leave it in a vertical position. In this fashion, the barrel serves as a small open-top tank, and cap management is achieved with punch downs. The other method is to fill the barrel the same way, replace the head and seal in the must. The barrel then can be laid on a rack, but it needs to be spun to wet the cap and achieve extraction. It’s through this more complicated and labor-intensive method of replacing the barrel heads and spinning—at least twice a day—that winemakers say they achieve the full benefits of introducing oak to fermenting must.

Specialized process for small lots
The laborious process of barrel fermentation often means that winemakers at smaller wineries use the method sparingly and only for certain lots.

One such winemaker is David A. Jeffrey, owner of 1,500-case Calluna Vineyards in Windsor, Calif. He said he uses a small amount of barrel fermentation after learning the method while working at Chateaux Quinault in St. Emilion, France.

Jeffrey said that for barrel fermentation he only uses fruit from the 1.25-acre “Colonel’s Vineyard” portion of his 12-acre estate. “At this point I don’t think I’d do 100% of my wine that way,” he said. “I want to highlight and do something different with that vineyard.” Jeffrey makes two Bordeaux blends as well as a single-vineyard Merlot in addition to the Colonel’s Vineyard Cabernet, which sells for $60 on the winery’s website.

Cabernet is often cited as the red varietal that most benefits from barrel fermentation because it has the flavors and structure to coalesce with new oak. Varietals with less tannin structure could be overwhelmed by oak during barrel fermentation. New oak is also vital. Several winemakers said barrel fermentation just isn’t worth the effort unless you’re using new oak. Because the method is best used with robust Cabernet and new oak barrels, it’s not surprising that red barrel fermentation has found many proponents in Napa Valley and Sonoma County, where Jeffrey lives.

Jeffrey said fruit from his vineyard is sorted on multiple tables and dropped directly into a macro bin. That bin is then moved over to the barrel room, where Jeffrey and his staff scoop the berries out of the bin with buckets to transfer to barrels. He said he uses special barrels by Tonnellerie Baron that feature a small hatch on one head. Using a funnel, the must is poured in through this hatch. The hatch is then sealed, and the barrels are gently lowered onto racks.

Jeffrey’s racks for barrel fermentation are made by Western Square and outfitted with wheels at the point where the barrels rest on the racks. The wheels are essential because the best way to manage a cap during barrel fermentation is to spin the barrel. “It’s a lot of labor to do that, but it’s only eight barrels, so it’s not the end of the world,” Jeffrey said. “But you have to make sure you have the capability and the time and the manpower.”

Monitoring fermentation is trickier when it’s happening in a barrel. During fermentation, Jeffrey said he regulates temperature by keeping the barrels in a warm room at about 75º F. To check the temperature of the must he slides a thermometer through the bunghole. One of Jeffrey’s barrels has a Plexiglas head that allows him to watch fermentation.

“I occasionally pull samples from the bunghole. It is a pain,” Jeffrey said. “Realistically, I monitor by observation: It is clear when the fermentation is proceeding due to the gas coming out of the bunghole. As that slows down, fermentation is obviously ending.” Jeffrey added that he monitors for sulfides with his nose. After a few weeks he pulls samples for tasting to make a judgment on pressing.

When it’s time to press, Jeffrey said he lifts the barrels up with a forklift, opens the hatch to drain the free run and then pulls out the fruit with a small rake designed to pass through the Baron barrel hatch. “The way I view it is with this process you’re obviously exposing the must and the wine earlier in the process,” Jeffrey said. “You’re seeing new oak before there’s any alcohol. It also is the new oak being exposed to the heat of fermentation.”

While the method has been growing in popularity, many winemakers said it’s best used only for wines that can match the oak. Bob Levy, director of winegrowing for Harlan Estate in Oakville, Calif., said the method has found a use for Harlan’s Bond Estates label.

“We feel that in certain cases it offers an opportunity to allow very gentle extraction for a very powerful and concentrated wine, when necessary, which is to say we do not feel it serves a universal purpose for all fermentations. It is yet another ‘tool’ we choose to use in those cases where we feel it is appropriate.”

Smaller, more selective fermentations
Austin Peterson, winemaker at the premium Ovid winery situated atop a peak east of St. Helena, Calif., employs barrel fermentation for a small portion of the winery’s estate vines. He said the beauty of barrel fermentation is that it allows him to pick row-by-row, ensuring optimal ripeness. He said he has also been able to identify certain areas of a vineyard that respond well to barrel fermentation. For fermenting such a small amount, Peterson said barrels make a lot of sense.

The method also enables him to match grapes with intense, robust flavors to new oak, resulting in a great richness and integration to the wine. “Where it does well, we really like the results,” he said.

The exact amount of barrel fermentation varies each vintage, but Peterson said it runs around 10% to 15% of the winery’s limited production of less than 1,000 cases. The average retail price for the Ovid Napa Valley is $200, and the winery’s second label “Experiment” retails for $90.

At Ovid, Peterson’s crew destems grapes with a Bucher Vaslin Delta E-1, sorted on multiple tables and dropped from the main crush pad into upright barrels. The barrel heads are reinstalled, and the barrels are lowered onto racks and moved to a cave for cold soak. For primary fermentation, the barrels are moved to the winery’s machine room, where the temperature hovers around 80º to 85º F. The barrels rest on single OxO racks that can be moved by forklift and also enable Peterson and his staff to spin the barrels, which they do one to five times a day.

Peterson said he installs a solid bung—hand tightened—and starts the spin with a half-turn. Once he feels the cap start to flip, he’ll give the barrel a full turn. To monitor fermentation, Peterson employs a stainless steel tube to punch through the cap and separate some juice from berries.

At press time, Peterson said he lifts barrels with a forklift and then spins them so the bunghole is above a sump with a screen. He will then pull the bung to drain the free-run wine, lowers the barrel back down and rolls it off the rack. He removes the head and either shovels out the remaining fruit or tips it directly into the press.

What barrels to use?
Choosing what barrels to use for fermentation has been a deliberate process based on the varying characteristics of the vineyard, Peterson said.

“We keep all of our barrels separate through the first year so that we can evaluate how each cooper, toast level and forest blend works with each part of our vineyard,” he said. “Having done this for a number of years, we have started to identify which barrels we like for each parcel. We end up aging the barrel-fermented wine in some of the barrels we ferment it in, so we tend to choose them based on what has historically complemented that lot over the course of a year.”

For Cabernet Sauvignon, Peterson said Taransaud medium-plus and Sylvain medium-plus has worked well—as has a barrel or two from French cooperage Orion.

Peterson noted that it’s not just the labor; one also has to keep in mind the logistics involved in dedicating some barrels for fermentation rather than aging.

“It’s really labor intensive to get the fruit into the barrel,” he said. “You’re filling twice as many barrels as you’ll use for wine storage.”

Several winemakers confirmed this math, saying that two barrels filled for fermentation will yield one barrel of wine for aging. So while space and labor costs should be of primary concern, the method is not as much of a burden in terms of dollars if you’re already set on purchasing new oak. “You’re buying the barrels anyway; the cost is the amount of labor and the time it takes,” Peterson said. The extra barrels needed for barrel fermentation can be used to store wine fermented in tanks.

What exactly is happening to the wine as it ferments in barrel is not clear. Dr. Anita Oberholster of the University of California Cooperative Extension has studied mouthfeel and wine aging. She said that while most research has gone into barrel maturation, not fermentation, a sensory study of the ellagitannins that could be extracted from new barrels found them to be described as “mouth-coating and astringent.”

And while the oxygen moving through the barrel would be utilized by the yeast and not be available for polymerization, there could still be an effect. Wood tannins could induce polymerization on monomeric pigments such as anthocyanins, and the products of this can confer a finer astringency with an increase in the perception of viscosity. “The combination of these could be described by some as softer tannins and mouth-coating tannins,” she said. 

Riding a roller coaster
Caldwell Winery in Napa’s new Coombsville AVA has made a significant commitment to barrel fermentation for several years. The winery produces 4,500 cases that include a limited amount of premium wines under the Caldwell Platinum, Gold and Silver labels that range in price from $120 to $225 per bottle as well as 1,500 cases of its red blend Rocket Science, which sells for $48, and several other single-varietal wines.

Director of winemaking Marbue Marke said that in order to make barrel fermentation a success, one has to have the ability to relinquish some control once the must starts to ferment in the barrel. “If you’re not used to natural fermentation, barrels won’t work for you,” he said. “As long as you’re comfortable with riding that roller coaster, you’ll be fine.”

Caldwell barrel ferments about 60% to 80% of its production each year. Marke said he hires a cooper to remove barrel heads for filling. Standing in front of a barrel outfitted with a Plexigas head, Marbue pointed out the whole berries and small cap to illustrate the benefits of barrel fermentation. “The free run doesn’t get affected by breaking seeds at all,” he said, adding that the percentage of cap not submerged is just a fraction of that in a tank.

Marke said he “lets the grapes tell” how much to barrel ferment each harvest. For the 2011 harvest, Marke said he did less fermentation in barrel because of the difficult vintage. He added that if a lot is spread out over 20 barrels, it could be a challenge to adjust additions for the volume and dynamics of each barrel. It’s also much easier to manage the fermentation temperature in a tank than a barrel.

The barrels at Caldwell are stacked on an OxOLine rack system. These racks, developed in partnership with Baron’s barrel-fermentation system, facilitate easy spinning but can’t be moved.

Marke said his staff members use a pneumatic lift system that can pull the barrels out of the racks. OxO also makes a single-barrel modular system that allows for easier moving, and Marke said he’s found that these are far easier than employing barrel fermentation on chocks.

Marke declined to name the cooperages he uses for barrel fermentation, adding that barrel fermentation is not the sole factor in choosing oak.

One day late in the 2011 crush, Marke had cellar workers racking out of a puncheon that had been used for barrel fermentation. The workers used a pump to rack the free run through a tube screen and into a small stainless tank. Once the free run had been pumped out, Marke said the workers would use a customized forklift attachment to tip the rest of the fruit out of the puncheon into the basket press. The job entailed as many as four workers and illustrated Marke’s point that every step of the winemaking process requires extra work with barrels as opposed to tanks.

For a winery like Caldwell, though, Marke said the method makes sense considering the winery’s 67-acre estate vineyard is home to nine varieties and several different clones. The winery has eight clones of Cabernet Sauvignon alone.

Using barrels enables Marke to pick what he wants, and the small fermentations give him a full palette when it’s time to create the final blends. “This vineyard is in an amazing climate that can make excellent wine in any vintage,” he said.

Ehren Jordan, winemaker at Failla Wines in St. Helena, Calif., said that during the past harvest he did 50 to 60 barrel fermentations. He said the method is best for Bordeaux varieties and sometimes Syrah.

One of the benefits of using the method is that it allows the winemaker the option of lengthening the maceration period. The tight head space can easily be gassed with a little dry ice, and it’s up to the winemaker to decide how long to leave it.

Jordan, who focuses on Pinot Noir for his Failla label, doesn’t employ barrel fermentation for much of his own wine, but he does quite a bit for custom crush clients. He said it’s easy for clients to taste the difference of barrel fermentation, but some balk at the expense. Factoring in the cooperage costs to remove barrel heads and the extra labor, Jordan estimated that barrel fermentation could cost hundreds of extra dollars per barrel.

“Every single time we’ve taken a lot and peeled off two, three barrels and done barrel ferments, the client tries it and they look at you and say, ‘Why didn’t you do this for everything?’ Then you tell them how much it costs and they go, ‘Whoa, whoa,’” he said. “If you make certain kinds of red wines, it’s an amazing tool, but they need to sell at a price point that allows for the added costs.”