Carbonic maceration is a winemaking technique where whole, uncrushed grapes ferment inside their own skins in an oxygen-free environment, producing wines that are lighter, fruitier, and softer than those made by conventional methods. It’s the process behind Beaujolais Nouveau and a growing number of natural wines, and it works by triggering fermentation inside each individual grape berry rather than in a vat of crushed juice.
How It Works Inside the Berry
In conventional winemaking, grapes are crushed to release their juice, and yeast is added (or naturally present) to convert sugar into alcohol. Carbonic maceration flips this sequence. Whole grape clusters are placed into a sealed vessel that’s been flooded with carbon dioxide, creating an atmosphere with no oxygen. The CO2 is absorbed by each berry, filling it to roughly 50% of its internal volume. This forces the grape’s metabolism to shift from normal aerobic respiration to a type of anaerobic fermentation that happens entirely within the intact fruit.
This intracellular fermentation occurs without any yeast involvement. Enzymes naturally present in the grape flesh break down a small amount of sugar into alcohol, typically producing 1.5 to 2% alcohol inside the berry. At the same time, the malic acid content (the tart, green-apple acid found in grapes) drops by roughly half. The process also generates a distinctive set of aromatic compounds that give carbonic maceration wines their signature character.
After this anaerobic phase, the berries are pressed, and the resulting juice finishes fermenting conventionally with yeast to reach its final alcohol level. So carbonic maceration is really just the first stage of a two-part process, but it’s the stage that defines the wine’s personality.
Why These Wines Taste Different
The intracellular fermentation creates a specific aromatic profile that leans heavily toward fresh fruit, flowers, and candy-like sweetness. Studies on wines made this way have identified dozens of volatile compounds responsible for these flavors, with esters playing a starring role. Isoamyl acetate, which smells like banana and bubblegum, is one of the most recognizable. Other prominent compounds contribute notes of green apple, pear, citrus, and floral tones like rose and honey.
Several of these aromatic compounds are present at concentrations well above the threshold where humans can detect them, meaning they don’t just subtly influence the wine. They dominate it. This is why carbonic maceration wines often taste like a fruit bowl compared to conventionally made versions of the same grape variety. The overall aromatic profile tends to cluster around fruity, floral, and sweet descriptors rather than the earthy, spicy, or savory notes associated with traditional red winemaking.
Lower Tannins, Brighter Color
Because the grapes aren’t crushed at the start, skin contact during the anaerobic phase is minimal compared to conventional fermentation, where crushed skins sit in the juice for days or weeks. This means significantly less tannin extraction. In traditional red winemaking, tannin extraction from grape skins and seeds typically falls somewhere between 10% and 58% of what’s available in the fruit, with averages around 22 to 27%. Carbonic maceration pulls out far less, which is why these wines feel soft and smooth rather than grippy or drying on your palate.
Anthocyanins, the pigment molecules responsible for red wine’s color, are water-soluble and extract relatively easily even with limited skin contact. So carbonic maceration wines often have a vivid, bright purple-red hue despite their light body. The combination of intense color with low tannin is one of the technique’s visual and textural trademarks.
Carbonic vs. Semi-Carbonic Maceration
True carbonic maceration involves filling the fermentation vessel with CO2 from an external source before adding the grapes. Every berry enters a fully anaerobic environment from the start, and the intracellular fermentation proceeds uniformly across the batch.
Semi-carbonic maceration, which is far more common in practice, skips the external CO2. Instead, whole grape clusters are loaded into a tank and sealed. The weight of the grapes on top crushes the berries at the bottom, releasing juice that begins fermenting conventionally with ambient yeast. That yeast fermentation produces CO2 as a byproduct, which rises and blankets the intact berries above, triggering intracellular fermentation in those upper layers. The result is a hybrid: some juice fermented traditionally, some fruit undergoing true intracellular fermentation. Most Beaujolais Nouveau is made this way.
The distinction matters because semi-carbonic wines tend to have slightly more tannin structure and complexity than fully carbonic versions, since a portion of the fruit is effectively undergoing conventional maceration from the start.
Which Grapes Work Best
Gamay is the grape most closely associated with carbonic maceration, largely because of its long history in Beaujolais. But the technique works across a surprisingly wide range of varieties, and its effect on each grape is different.
For aromatic grapes like Shiraz and Muscat, carbonic maceration can amplify the variety’s natural character, making it more intense and expressive. For relatively neutral grapes like Carignan and Gamay, it adds a layer of fruity complexity that the grape wouldn’t produce on its own. With some varieties, like Cabernet Sauvignon, the proportion of fruit that needs to undergo the process to noticeably affect the finished wine can range from about 20% to 85%, meaning winemakers can blend carbonic-macerated fruit with conventionally fermented wine to dial in the style they want.
There are also grapes where the technique is less desirable. Concord grapes and certain French-American hybrid varieties can have their distinctive character muted or masked by the carbonic process, making them taste less like themselves rather than more.
What to Expect in the Glass
If you pick up a bottle made with carbonic maceration, expect a wine that drinks young and fresh. These wines are typically released within weeks or months of harvest rather than aged for years. The flavor profile will lean toward ripe red fruits, banana, bubblegum, and sometimes a juicy, almost candied quality. The body will be light to medium, tannins will be barely noticeable, and the acidity will feel gentle thanks to that reduction in malic acid during the intracellular phase.
Serving temperature matters more than usual with these wines. Slightly chilled, around 12 to 14°C (55 to 57°F), keeps the fruit flavors vibrant and prevents the low-tannin structure from feeling flat. Many people who think they don’t like red wine find carbonic maceration wines approachable precisely because they lack the astringency and heaviness of conventionally made reds.
Beyond Beaujolais, carbonic maceration has become a favorite tool in the natural wine movement worldwide. Winemakers in Australia, Spain, South Africa, and the United States increasingly use it with varieties like Grenache, Cinsault, and Mourvèdre to produce fresh, gulpable reds meant for immediate enjoyment.