What Do Wines Aged in Concrete, Clay and Glass Taste Like?
Oak and steel may be the wine world’s golden children, but when it comes to vinification vessels, the options go much further. Though hard to believe now, oak and steel weren’t always winemakers’ top picks—and much of the modern wine world is taking a turn back to its roots. Today, winemakers worldwide are choosing to vinify wines in alternative vessels, bringing unique flavor profiles to the final products. Get to know three of these materials, here.
If there were a Goldilocks of winemaking vessels, concrete would undoubtedly be it. Like oak, concrete’s porous nature allows oxygen to penetrate through the vessel and interact with the wine. Unlike oak, which commonly imparts notes of vanilla, baking spice, or coconut, concrete aged wines develop in a "flavorless" environment (in that way, the material is similar to steel).
“Concrete aged wine has a little more pep in its step,” says Pax Mahle, owner and winemaker at Pax Mahle Wines. “We typically press still-fermenting wines [with minimal residual sugar levels] into the concrete vessel where it will age, which produces CO2. This CO2 protects the wine from any excess oxygen exposure, ensuring that the wine is bright, fresh, and filled with energy.”
In addition to those micro-oxygenation benefits, concrete vessels are also generally more cost-friendly than oak barrels, and, just like oak, come in a variety of shapes and sizes (hello, concrete eggs!).
Fermenting and aging wine in clay vessels is a practice that dates back over six millennia, with roots near present-day Georgia. Despite the material’s past decline in use—mostly due to the rise in popularity of steel and oak—vinification in clay is now on the rise. "Clay is the most neutral material, thus allowing the grape to fully express its identity,” says Mateja Gravner, winemaker at Friuli-based Gravner Wines.
Depending on where the winemaking is being done, clay vessels go by a variety of names: qvevri in Georgia, amphora in Italy, and tinaja, in Spain, are just a few. “The shape of the clay vessel has an important role too,” explains Gravner. “The amphora shaped vessel—we use the Georgian qvevri—allows the mass to naturally rotate (by convection movement), as a consequence of the fermentation process.”
Similar to concrete, vinification in clay provides a happy medium between steel and oak, in that clay is a porous environment, without oak's flavor impact. Wines aged in clay will therefore benefit from the micro-oxygenation effects that wood provides, yet retain their fruit-forward character, uninfluenced by external flavors.
Unlike concrete and cement, whose porous materials permit contact between oxygen and wine, vinification in glass is done in an airtight space, often referred to as a reductive environment, making the vessel more similar to stainless steel than wood. "Using glass is pretty much the most reductive way that I know to make wine,” says Abe Schoener, founder of The Scholium Project and winemaker at Red Hook Winery. “One can use stainless steel tanks, or other completely sealed tanks, but I can't imagine locking them down to such a totally reductive environment.”
In addition, glass vinification is usually done in significantly smaller sized vessels than those made of oak or steel. “I’ve heard of custom made larger glass vessels, but they have to be embedded in wood, as they can't support themselves on their own, due to fragility and/or weight,” explains Schoener. ”However, the great thing about vinifying in such small volumes, is that it changes the physics of the whole winemaking process: lees contact, etc.”
Schoener notes that his glass-vinified wines are sampled as rarely as possible, for the sake of keeping oxygen contact to a minimum. He explains that each time that the vessel is opened and sampled, it is then immediately topped off to its original level. “Every time we open that little glass thing, we bring the liquid level right back up to the top, because we want to emphasize that reductive environment.”
Whether reduction or micro-oxygenation are the goal, these three materials provide uniquely different environments for vinification, leading to a variety of flavor profiles. The best way to understand the effect of these materials on the final wines? Tasting, of course!