Carbonic maceration, explained.
Fermentation inside the cherry, not around it.

Most coffee processing starts by breaking the cherry open: pulped for washed, skin intact but exposed to air for natural drying. Carbonic maceration skips that step entirely. Ripe cherries go into a sealed tank exactly as picked, and the tank is flushed with carbon dioxide, sometimes topped up from a CO2 canister until the air inside is fully displaced.

With no oxygen and no wound in the skin, fermentation cannot start on the outside the way it normally would. Instead it begins inside each intact berry. Enzymes inside the fruit break down its own sugars under pressure, days before the cherry is ever pulped or laid out to dry. The fruit effectively ferments itself from within, which is why the flavor swings so far from anything a washed or plain natural lot produces.

Carbonic maceration is not a coffee invention. It is a century-old technique from Beaujolais, where whole grape clusters ferment intact in CO2-filled tanks to produce the region's light, fruity reds without the tannin a crushed fermentation would add. Coffee producers adapted the same idea to cherries only in the last ten years or so, chasing the same result: fruit character that a conventional ferment never reaches.

The borrowing explains the confusion around the term. In winemaking, carbonic maceration is one clearly defined method. In coffee, it arrived alongside a wave of other fermentation experiments at once, and the labels blurred together on bags and menus before any of them settled into consistent use.

This is the distinction most coffee writing gets backward. Anaerobic is the broad category: any fermentation with the oxygen excluded. The cherries can be pulped or whole, the tank can be sealed with an inert gas or simply closed and left to purge itself. Carbonic maceration is one specific version of anaerobic processing — the cherries must stay whole, and the tank must be saturated with carbon dioxide specifically, not just starved of oxygen in general.

So every carbonic maceration lot is anaerobic. Most anaerobic lots are not carbonic maceration. The cherries were pulped first, or the gas was never CO2-specific. And neither term covers co-fermentation, where a producer adds fruit, a culture, or a spice to the tank. A strawberry-forward lot is almost always a co-ferment, not a carbonic maceration. Nothing goes into a true carbonic maceration tank except cherries and carbon dioxide.

Fermenting whole fruit under pressure concentrates flavor rather than diluting it. Expect intense, candied fruit — a register closer to jam or dried berry than fresh fruit. Acidity reads lower and rounder than in a washed or pulped-anaerobic lot: fermenting inside the intact cherry softens the acid the same way carbonic maceration softens tannin in wine. The finish tends to run long and sweet, and a well-made lot holds that sweetness without tipping into solvent or vinegar notes.

The failure mode is the same one anaerobic lots share: a tank held too long or too warm reads as boozy heat or nail polish rather than fruit. The technique amplifies whatever precision the producer brought to the fermentation, for better or worse.

Carbonic maceration is slower and riskier than almost any other processing choice available to a producer. The tank has to be monitored for days, the CO2 level has to be held, and a single tank that runs too warm or too long is unsalvageable. There is no rinsing a spoiled batch clean the way a washed lot can recover from a short mistake. Producers run it only on small, hand-picked volumes as a result, which is why lots are scarce and priced well above a comparable washed coffee from the same farm.

The same risk explains the inconsistency. Two carbonic maceration lots from the same region, even the same season, can taste meaningfully different depending on how tightly the producer controlled temperature and CO2 saturation. Buying one is closer to buying a vintage than buying a spec sheet.

Filtered methods show a carbonic maceration lot better than espresso — a V60, Kalita, or immersion brewer lets the fruit come through clean instead of compounding it into a syrupy mess. Grind a shade coarser than your usual filter setting and pull the extraction slightly shorter; these cherries already gave up a lot of sugar and acid inside the tank, and pushing a long, hot extraction on top of that tips fruit into sourness fast. Skip milk: it flattens exactly the aromatics you paid the premium for.

Taste one cup before committing to how you drink the rest of the bag. A lot this concentrated rewards a slightly different recipe than your everyday coffee, and the fastest way to find it is by tasting, not by guessing at a ratio in advance.