Fermentation is a magical time of transformation. A time when grapes shift from innocent juicy berries to wines with depth of soul.
Wineries use fermentation vessels to ferment juice into wine. Common wine fermentation vessels include oak barrels, stainless steel, clay jars (a.k.a., talhas, tinajas, amphora, qvevri), concrete, stone (lagares), glass, and even plastic. The winemaker will select the fermentation vessel based on the style of wine, price point, and regional traditions.
Here’s what you need to know.
Fermenting Wine in Oak Wine Barrels
Oak wine barrels can be used to ferment wine. As you can imagine, the insides of the barrel are porous and allow some transference of oxygen between the must (fermenting wine juice) and the outside of the barrel. Fermenting in oak can give the wine more mouthfeel and texture.
A winemaker may opt to use an oak wine barrel for fermentation to create a fuller-bodied wine, like a Cabernet Sauvignon, or even a full-bodied Chardonnay.
Oak wine barrels used for fermentation can be new oak (uncommon) or used oak. New oak will transfer barrel flavors to the fermenting wine, like spice, coffee, toast, or vanilla.
Used oak will impart less flavor to the wine. And if the winemaker wants to increase the mouthfeel in the wine but not transfer any flavor or aromas, then she’ll use what’s called neutral oak.
These are barrels that have a neutral toast to them or have been used over several vintages and no longer impart flavors or aromas.
One drawback to fermenting wine in oak barrels is that the winemaker has little control over the fermentation temperature. This can be challenging with aromatic white wines or red wines that need to stay within a certain temperature range for optimal fermentation.
Another drawback to fermenting wine in oak barrels is that they are rather small for large-scale production.
This means that if a producer is fermenting a substantial amount of wine in oak barrels, and they will have to monitor multiple fermentations concurrently, adding to overall labor costs.
Fermenting Wine in Oak Foudres
Oak foudres are large fermentation tanks made out of oak. They can be anywhere from 300 liters to upwards of 5,000 liters. These large oak tanks do little to impart any oakiness to the wine, like spice notes, but they can still add some texture to the wine through micro-oxygenation.
Here’s a great time-lapse video construction foudres.
Fermenting Wine in Stainless Steel
Stainless steel wine tanks vary in size from a few liters to over 100,000 liters with industrial winemaking. These tanks are considered inert, meaning that they do not impart any flavors or aromas to the wine, and they don’t alter the texture of the wine.
Another benefit of stainless-steel wine fermenters is that they can be outfitted with glycol jackets that can control the temperature of the fermentation.
This is a critical factor when making aromatic wines.
Fermenting Wine in Clay Jars
Perhaps the most traditional of wine fermentation vessels, clay jars have been used for millennia to ferment wine.
These jars can range in size and are popular with wine producers seeking a more traditional image. You may fear the term amphora (Greece), qvevri (Georgia), tinaja (Spain), or talha (Portugal) – each refers to clay jars used for winemaking.
Fermenting Wine in Concrete
Concrete is another inert fermentation vessel, imparting no flavors, aromas, or textures to the wine.
Concrete naturally regulates the temperature of the fermentation because it takes longer to warm up or cool down, unlike a small wine barrel that’s more susceptible to the ambient temperature.
One downside to concrete is that once the concrete fermentation vessel is set, or poured, the winery cannot make any changes to the winery layout or production size.
Fermenting Wine in Lagares
Over in Portugal, they have a long tradition of lagares, or open fermentation vessels made out of stone. These wide, but shallow, fermentation vessels allow the winery to monitor color extraction in the base wine that is destined for Port.
Helpful Tip: Go check out this post on how they make Port wines (I love Port!).
Fermenting Wine in Glass
Like stainless steel, glass is an inert wine fermentation vessel. It can be used for smaller production winemaking, or may even be used to line other types of fermentation vessels.
For example, in Pays Nantes, in the Loire region of France, some producers use clay fermentation tanks lined with glass to ferment their wine.
Fermenting Wine in Plastic
Food-grade plastic can be used to ferment wine. It is also considered an inert material that doesn’t impart any flavors or textures to the wine. This is what I use for my garage winemaking. It works!
With all of these options, how does a winemaker decide what type of fermentation vessel to use?
Sometimes this comes down to tradition.
For example, a producer may want to capitalize on a winemaking region’s history, and so opt to ferment in clay jars, or amphora.
This may be a selling point for their target market.
A wine’s style can also dictate the fermentation vessel.
In this case, an aromatic white wine, like Riesling or Sauvignon Blanc, really needs to be fermented in something where the winemaker can monitor and control the fermentation temperature closely. Stainless steel may be the most prudent option.
Why pick just one when you can use many?
A winemaker may decide to ferment wine in separate lots using different types of fermentation vessels.
This allows for blending later on in the winemaking process and can increase the quality and complexity of the final wine.
Why is the wine fermentation vessel important?
If you are the wine-curious sort, then you will start to notice references to the fermentation in the winemaking notes included on wine labels or as part of the technical sheets for wines.
It’s helpful to know that this is what they’re talking about, and not feel overwhelmed by wine jargon.
And if you want to engage a winemaker in a nerdy conversation, then you can ask them about their fermentation vessels and sound really smart.
But if you’re seriously into wine, you may begin to notice differences between wines fermented in different types of fermentation vessels.
While picking out that level of nuance is probably for the pros, it’s always fun to close your eyes, swirl, sip, see if you can unravel what’s in the glass … and then maybe even swallow instead of spit!