Carbonic Maceration — Beaujolais Nouveau to Cru Beaujolais

Carbonic maceration is a winemaking technique in which whole, uncrushed grape bunches are loaded into a sealed vessel filled with carbon dioxide, creating an anaerobic environment that triggers fermentation inside each intact berry through enzymatic action rather than yeast. French scientist Michel Flanzy first developed the process in 1934 while experimenting with carbon dioxide as a means of preserving harvested grapes. Although his preservation goal failed, the unexpected fermentation that occurred led him to propose an entirely new vinification method. The technique subsequently shed light on an ancient traditional process long practiced in Beaujolais, where whole-bunch fermentation in sealed vessels had been the norm for generations, and it became closely identified with the Gamay grape of that region.

• Invented by Michel Flanzy in 1934 as an accidental result of a grape preservation experiment using CO2
• Whole grape clusters ferment in a sealed, CO2-saturated vessel; grapes at the bottom are crushed by gravity and undergo conventional yeast fermentation simultaneously
• Semi-carbonic maceration, the dominant Beaujolais variant, uses naturally produced CO2 from crushed base grapes rather than pumped gas
• The technique is closely associated with Gamay in Beaujolais, and also with Tempranillo in Rioja Alavesa, where carbonic maceration has deep traditional roots

The process unfolds in four stages: vatting of intact bunches in a CO2 atmosphere, the maceration-fermentation phase, pumping off the free-run juice, and pressing followed by a second conventional fermentation. Inside each intact berry, the anaerobic environment triggers a shift from respiratory to fermentative metabolism. Glycolytic enzymes convert sugars to ethanol, reaching approximately 1.5 to 2% ABV, at which point the berry usually splits and juice escapes. Crucially, around 50% of malic acid is also converted during this intracellular phase, raising pH by roughly 0.25 and producing glycerol plus a range of aromatic compounds including esters. Optimal conditions recommended by research are around 30 to 32 degrees Celsius for five to eight days. After the maceration phase, the remaining juice undergoes standard Saccharomyces cerevisiae fermentation, completing the alcohol conversion.

• Intracellular fermentation produces approximately 1.5 to 2% ABV before the berry splits and conventional yeast fermentation takes over
• Around 50% of malic acid is converted during carbonic maceration, raising berry pH by roughly 0.25
• Research recommends temperatures of around 30 to 32 degrees Celsius for five to eight days for optimal carbonic maceration character
• Elevated glycerol accumulation during the anaerobic phase contributes roundness and a soft, silky mouthfeel to the finished wine

Carbonic maceration produces wines of notable aromatic freshness, with dominant red fruit character including cherry, strawberry, and raspberry, alongside estery volatile compounds such as bubblegum and cinnamon often described as hallmarks of the style. Because cell walls remain intact during the maceration phase, extraction of harsh skin and seed tannins is dramatically reduced, resulting in wines that are light in color, soft in texture, and low in astringency. Acidity is present but rounded because of malic acid conversion during intracellular fermentation. Beaujolais Nouveau, bottled only six to eight weeks after harvest, epitomizes this style: intensely fruity, higher in acidity, very low in tannin, and designed for immediate consumption. Premium Cru Beaujolais wines, using longer macerations and older vines on granite and volcanic soils, develop additional depth, minerality, and aging potential of five to fifteen years or more.

• Characteristic aromas include red cherry, strawberry, raspberry, and estery notes of bubblegum and cinnamon; these arise from specific volatile compounds produced during intracellular fermentation
• Tannin levels are significantly lower than in conventionally fermented wines because cell walls remain intact, limiting extraction from skins and seeds
• Malic acid conversion softens acidity; color depth and tannic sensation are strongly influenced by the temperature and duration of the carbonic maceration step
• Beaujolais Nouveau is bottled six to eight weeks after harvest; Cru Beaujolais from top appellations such as Morgon and Moulin-a-Vent can age for a decade or more

Beaujolais Nouveau is a vin de primeur released at 00:01 am on the third Thursday of November each year, a date established by INAO in 1985. It relies on short macerations of a few days to maximize aromatic volatility, minimize tannin, and achieve rapid bottle-readiness. By contrast, the ten Cru Beaujolais villages, situated in the northern part of the region on predominantly granite and schist soils, employ longer macerations to extract greater structure, color, and aging potential. In the winery, Cru producers can legally choose from carbonic maceration, semi-carbonic maceration, or traditional vinification. Many of the most celebrated Cru estates, including natural wine pioneers in Morgon, employ semi-carbonic maceration with whole bunches, minimal sulfur additions, and ambient yeast fermentation, producing wines of remarkable depth and terroir definition that bear little resemblance to the commercial Nouveau style.

• Beaujolais Nouveau: released the third Thursday of November each year since 1985; in 2024, around 14.3 million bottles were sold worldwide, representing roughly 22% of total Beaujolais production
• Cru Beaujolais producers may choose carbonic maceration, semi-carbonic maceration, or traditional vinification depending on their style goals
• The ten Crus, from north to south, are Saint-Amour, Juliénas, Chénas, Moulin-a-Vent, Fleurie, Chiroubles, Morgon, Régnié, Brouilly, and Côte de Brouilly
• Natural wine pioneers in Morgon use semi-carbonic maceration with whole bunches, no added yeasts, and minimal or no sulfur additions until bottling

Château Thivin, the oldest estate on Mont Brouilly in Côte de Brouilly, has been owned by the Geoffray family since 1877 and now spans 30 hectares across more than ten distinct plots. The family was instrumental in creating the Côte de Brouilly appellation in 1938 and remains the reference producer for the cru, using traditional whole-cluster fermentation followed by aging in large old oak foudres. Domaine Marcel Lapierre in Morgon represents the natural wine tradition: Marcel Lapierre took over the domaine in 1973 and, from 1981 onward with the guidance of researcher Jules Chauvet, began vinifying without sulfur or selected yeasts. Alongside Jean Foillard, Guy Breton, and Jean-Paul Thévenet, a group American importer Kermit Lynch dubbed the Gang of Four, Lapierre spearheaded a return to low-intervention carbonic maceration that inspired winemakers worldwide. The estate, now run by Mathieu and Camille Lapierre, covers 18 hectares in Morgon and practices biodynamic farming. Les Vins Georges Duboeuf, founded in 1964 and producing more than 2.5 million cases of wine annually, remains the largest and most recognized Beaujolais negociant globally.

• Château Thivin (Côte de Brouilly): Geoffray family since 1877; 30 hectares across 10+ plots on ancient volcanic Mont Brouilly; whole-cluster fermentation in the traditional Beaujolais style
• Domaine Marcel Lapierre (Morgon): founded 1909; Marcel pioneered SO2-free semi-carbonic maceration from 1981 with Jules Chauvet; estate now farmed biodynamically by Mathieu and Camille Lapierre
• The Gang of Four (Lapierre, Jean Foillard, Guy Breton, Jean-Paul Thévenet): natural wine pioneers whose minimal-intervention carbonic maceration set a global benchmark for the style
• Les Vins Georges Duboeuf: founded 1964; over 2.5 million cases produced annually; the world's most prominent Beaujolais negociant and a leading global force in Beaujolais Nouveau

While carbonic maceration is most closely identified with Beaujolais, it also has deep historical roots in Rioja Alavesa in Spain, where it was reportedly the region's only winemaking method until the late 18th century. Today, Tempranillo-based vino joven wines from Rioja Alavesa, labeled maceracion carbonica, remain a celebrated regional tradition produced by estates such as Artuke and CVNE. Beyond Europe, the technique has gained significant traction in California, where producers working with Grenache, Syrah, and Pinot Noir use it to create lighter, more aromatic expressions, and in Australia among Grenache-based producers. The most common global adaptation is semi-carbonic maceration, where natural CO2 produced by crushed base grapes creates the anaerobic environment rather than pumped gas, offering aromatic lift and softened tannins with a more approachable structure. Recent research also points to carbonic maceration as a tool for reducing alcohol content in certain grape varieties, adding new commercial interest in the technique beyond its traditional flavor applications.

• Rioja Alavesa (Spain) has its own long-standing carbonic maceration tradition with Tempranillo, producing fresh vino joven wines labeled maceracion carbonica
• California producers work with Grenache, Syrah, and Pinot Noir using carbonic or semi-carbonic techniques for lighter, more aromatic styles
• Semi-carbonic maceration, where CO2 is generated naturally rather than pumped in, is more widely practiced globally and produces subtler carbonic character
• Research published in Food Chemistry (2023) found carbonic maceration can reduce alcohol by up to 3.7 degrees in free-run fractions, opening new lower-alcohol wine applications