Science

Why Winemakers Are Split on the Benefits of Concrete Eggs

Some winemakers promise this increasingly popular fermenting and aging vessel offers softer tannins and greater depth of flavor—but others are on the fence

With its unique convection currents and ability to impact tannins and acids, producers around the world have experimented with, embraced, or rejected concrete eggs for a variety of reasons. Photo credit: Alexander Rubin Photography.

Egg-shaped vessels are not new options for fermenting or aging wine. In fact, they’re one of the oldest wine vessels in the world, found amongst the ruins of ancient Georgia, Spain, and Armenia. In 2001, Rhône winemaker Michel Chapoutier tweaked the shape with the help of the French company Nomblot, designing an egg-shaped concrete tank in hopes that the spherical shape would channel celestial energy. Do these tanks converse with the cosmos? It remains a mystery, but the egg shape does allow for constant movement and continuous flow—benefits international winemakers are finding increasingly appealing.

Chapoutier was initially drawn to the concrete egg because of its shape—oblong and curved, with a smooth internal surface and a complete lack of corners. Principles of thermodynamics dictate that the continuous surface of the egg shape creates a vortex within the fermenter, allowing for the wine to move freely and the lees to suspend within the wine. “The concave shape of the egg adds a natural bâtonnage, rolling the lees in the bottom of the tank,” says third-generation winemaker Sebastian Zuccardi of Argentina’s Zuccardi. The shape—a nod to Roman amphora and other ancient vessels—and the depth of the concrete also allows for lower, more stable temperatures during fermentation, removing the need for artificial cooling. 

Compared to other clay vessels, Chapoutier’s main tweak to the tank was swapping in concrete—a neutral material that doesn’t impart extra flavors—over clay. Nombolt uses cement made from Loire sand, while Zuccardi uses rocks and clay from nearby rivers, adding an extra element of place to his wines. 

With its unique convection currents and ability to impact tannins and acids, producers around the world have experimented with, embraced, or rejected the vessel for a variety of reasons. Some enjoy how concrete egg fermentation adds a richer body and rounds out acidity in aromatic varieties, while others appreciate the body it adds to low-tannin grapes. Other winemakers just have a curious nature and see concrete eggs as another crayon in their box—a potential new tool to add to their arsenal.

The Bright Side of Concrete Eggs

Proponents of concrete eggs are using them to achieve a variety of different flavors, textures, and styles of wine. In Bordeaux, for example, wineries are adopting concrete vessels to help round out the tannins in newly introduced grapes like Marselan. In Napa, Cakebread Cellars’ winemaker Niki Williams is experimenting with adding touches of egg-fermented wine to bring a new element to the winery’s house Sauvignon Blanc. 

“Concrete offers a wonderful middle ground between a stainless steel tank—a vessel that does not allow any oxygen through—and an oak barrel, which allows much more oxygen to get into the wine,” says Williams. While stainless steel brings out boxwood and sulfuric characteristics in Sauvignon Blanc, she finds concrete allows for more character and minerality. “It adds more oxygen to the wine, allowing more dynamic fruit to come forward.”

Napa Valley-based Jeremy Carter, the winemaker for Tarpon Cellars, has always found concrete eggs enticing. He worked with the vessel in roles at now-shuttered Luna Vineyards and Chappellet and when he opened Tarpon Cellars in 2017, a concrete egg was a must, especially for aromatic varieties like Gewürztraminer. “I’ve always loved the texture concrete adds,” he says. “Having the lees in contact and circulating in that vortex in the bottom of the egg lends just enough texture to balance out the acid and lend a minerality and quartz-like quality to the grape.”

It’s also a vessel that makes sense for his process. If Tarpon Cellars aged Gewürztraminer in individual barrels, he’d have to stir each barrel twice a day. “It takes up a lot of time and energy,” he says. The round shape of the egg allows lees to circulate consistently.

Sebastian Zuccardi (above) uses rocks and clay from nearby rivers to make his concrete eggs, adding an extra element of place to his wines. Photo courtesy of Winesellers LTD.

In Argentina, Zuccardi has bet the farm on concrete. He has dozens of 1000- and 2000-liter concrete eggs for fermentation alongside 3000-liter concrete amphora and custom-made round concrete vats for aging Malbecs. “The roundness is really important to me,” he says. “You have no corners—everything is homogenous.”

He cites several reasons for the commitment to concrete. The first is flavor; concrete is a neutral environment, so it doesn’t impart additional flavors. “The end product shows you simply grape and place,” says Zuccardi. Second, concrete is a semi-porous substance, allowing for ever-so-slight micro-oxygenation, which is ideal for rounding out the Malbec that Zuccardi works with. 

Zuccardi also finds concrete eggs are efficient at temperature management. “We live in an area where the nights are very cold and the days are very warm,” he says. “With concrete, you have a thick wall [concrete is up to six inches thick] so everything is insulated. You save a lot of energy.”

The Argument Against Concrete Eggs

While concrete eggs may offer a wealth of benefits to some, it’s not a one-size-fits-all approach to winemaking. California sparkling wine house Schramsberg purchased several concrete eggs to experiment with for their still base wines. They worked with the eggs for a few vintages, but ultimately decided to get rid of the vessels this summer. “For our sparkling wine program, we found the base wines were not able to take full advantage of what the eggs provided,” says Matthew Levy, the marketing manager of Schramsberg and Davies Vineyards.

Concrete eggs were an inefficient use of time and space. Wines needed to rest in the eggs for nine to ten months, while stainless steel just needed two. “As we looked at the space that was being taken by the eggs, which together stored 860 gallons of wine, we realized we can fit four portable tanks that will hold 2,000 gallons of wine in the same space,” says Levy. “It just didn’t make sense to keep the eggs.” 

These vessels can also be temperamental. Concrete is a fragile material—too much pressure while washing will damage the walls and drastic temperature changes will crack the exterior. “We need to be very gentle,” says Zuccardi. “We just work with hot water and a brush.” These eggs are also enormously heavy, making it difficult to move them around a winery. 

Winemakers Lukas Papagiannis and Marco Prete of Barolo-based bhn Wines personally don’t see the point of concrete eggs. “I much rather use terracotta vessels,” says Prete. “They’re a fraction of the price and provide the micro-oxygenation effects of wood while capturing the character of the fruit.”

“I’m apprehensive to use concrete,” says Papagiannis. “A major component of concrete is CaCO3 (limestone), which is reactive. When in contact with wine, it can alter pH and TA by neutralizing the acidity in the wine. In terms of stability and perceived freshness, this isn’t ideal.” With less than a handful of scientific studies available exploring the benefits of egg fermenters, it’s an expensive vessel to invest in with uncertainty.

“I think if Instagram hadn’t existed, egg fermenters wouldn’t be popular,” says Matthieu Billecart of Champagne Billecart-Salmon. “I understand the idea of lees suspension, but we can suspend our lees in a regular tank by lowering the temperature. The egg is useless.”

Tarpon Cellars
For Tarpon Cellars’ winemaker Jeremy Carter (above left), a concrete egg was a must, especially for aromatic varieties like Gewürztraminer. Photo courtesy of Tarpon Cellars.

Experimenting with Concrete Eggs

Purchasing a concrete egg fermenter doesn’t mean upheaving or editing a winemaker’s entire practice. Williams is finding concrete eggs are excellent vessels for experimentation. It’s her first harvest with Cakebread Cellars and she’s already eyeing single-vineyard expressions of Sauvignon Blanc and Chardonnay fermented in concrete eggs. She’s also playing with Pinot Noir or Grenache—grapes where she wants to highlight the fruit—aged in concrete. 

None of these ideas are set in stone, but she knows that every vintage varies—especially in the era of climate change—and wants to have all the tools she may need to run with the grapes the year gives her. “Concrete gives us blending components,” she says. “It opens up different levels of textures and flavors we can play with.”

Currently, Carter is aging Gewürztraminer in a concrete egg. When money allows, he plans to buy another one. “If we could get another egg, I would love to experiment with some of our whites or make a skin-contact wine in there,” says Carter. “An egg is at the top of my Christmas list.”

Papagiannis was surprised when he visited California and spotted these vessels in almost every winery he visited. So he simply shrugged off the vessel as fad. “Winemakers just love to experiment,” he says.

Much like other new trends, perhaps concrete eggs are best used when matching materials to practices. “Remember, concrete isn’t a magical place that makes great wine,” says Zuccardi. For him, concrete eggs are an extension of his expression of place—a way for him to connect with the land. “Concrete is a natural material,” he notes. “It’s stone, sand, water, and sediment.” He works with a local craftsman to make concrete vessels out of soil from their land and water from the Andes mountains—materials that share the same origins as their wines.

“I’m not looking to make perfect wine,” says Zuccardi. “I’m looking to make a wine that talks about place. We make mountain wine. Everything we do is in relationship with the mountains—the climate conditions, the water that irrigates our soil, our vessels, and of course we’re mountain people. We’re not talking about perfection. We are talking about uniqueness and identity, and concrete is a great material to work in this manner.”

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By day, Kate is a writer, editor, and photographer covering the intersection between spirits, business, culture, and travel. By night, she’s a WSET-trained working sommelier at one of the top restaurants in Canada. She writes about strong drinks and nice wines for Forbes.com, Wine Enthusiast, Vogue, Maxim, InsideHook, People Magazine, Southern Living, Liquor.com, and The Toronto Star

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