At its heart, winemaking is an exercise in chemistry. While many ancient techniques are still used by vintners today, enterprising winemakers have pushed the boundaries of production to find new and exciting ways to turn grapes into something extraordinary. Carbonic maceration, considered a relatively modern technique, is used to create fresh and juicy wines around the world, but is particularly revered in the French wine region of Beaujolais.
Relying on a chemical reaction known as anaerobic fermentation to break down whole red grapes, carbonic maceration has become an increasingly prolific method of production, resulting in a surge in the popularity of carbonic wines over the past several years. And while these processes may be complex, what’s important to know is that they’re not different, but rather essential to each other.
Often served slightly chilled, red wines produced using carbonic maceration are well suited for a large range of foods, while their easy-drinking profiles and affordable price tags make them a go-to for consumers. Keep reading to learn more about this fascinating style of winemaking yielding lively and fruit-forward wines.
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The word anaerobic means “without oxygen,” and when applied to fermentation simply refers to an environment by which wine, specialty coffee, and even beer is made in an oxygen-free environment.
Jamie Goode, a wine writer and the author of “The Science of Wine: From Vine to Glass,” writes in his book: “The basis of carbonic maceration is the biochemical process of anaerobic fermentation, the breakdown of sugars to release energy in the absence of oxygen. Yeasts use this pathway even when oxygen is present, and the result is that sugar is broken down to alcohol and carbon dioxide.”
Rather than crushing the grapes and adding yeast to jump-start fermentation, carbonic maceration involves the addition of whole clusters of grapes and carbon dioxide gas into a sealed tank. After the grapes absorb the carbon dioxide, anaerobic fermentation begins when enzymes begin converting the sugar into alcohol, while also reducing the amount of malic acid inside each grape.
Once the alcohol reaches more than 2 percent, the grapes break open. But as VinePair explains, “typically, a winemaker will choose to press the grapes before this point, taking the fermenting juice out of its anaerobic environment and exposing it to oxygen. Yeast will then step in to finish the job, completing the fermentation of sugar into alcohol.”
Many producers utilize variations of a process called “semi-carbonic maceration.” While relying on the same chemical processes discussed above, semi-carbonic maceration employs carbon dioxide that is naturally created when grapes begin to break down. In this production method, the weight of the top portion of a tank of grapes slowly crushes the bottom section, causing them to release their juices. This juice along with ambient yeasts begins to ferment, creating carbon dioxide and forcing the still-intact whole grapes into anaerobic fermentation.
Some experts point to the 19th-century French scientist Louis Pasteur as the first to record how whole grape fermentation affects the flavor of wine. In 1934, Michel Flanzy, a French scientist and the director of the Narbonne wine research center, was the first to actually experiment with carbonic maceration. However, it is Jules Chauvet, a Beaujolais négociant who is often credited with pioneering the carbonic method beginning in the 1960s.
Wines that have undergone carbonic maceration are fruit-forward, light- to medium-bodied, low on tannins, and high in acid. Flavors such as raspberry, red cherry, cranberry, kirsch, and even banana can be common, though some of these flavors are more prevalent in nouveau-style wines meant to be consumed immediately.
One such example of this style is Beaujolais Nouveau, released annually to celebrate the region’s harvest and known for its sweet, bubblegum, and fruit-pop flavors. Simple and very young, Beaujolais Nouveau showcases a basic style of what carbonic maceration can achieve (but that can still be fun).