A term loosely thrown around when talking about wine with nerds like us. We're conscious of the vagueness of many of terms, though. So here, in short, is carbonic maceration (or maceration carbonique in French) explained:
Carbonic maceration is a winemaking technique that involves fermenting whole grapes in a carbon dioxide-rich environment. This process is used to produce wines that are fruity and low in tannins. Here are the basic steps involved in carbonic maceration:
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Grapes are loaded into a sealed tank, which is then filled with carbon dioxide gas. The carbon dioxide creates an oxygen-free environment, which helps to prevent oxidation of the grapes.
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The weight of the grapes at the top of the tank crushes the grapes at the bottom, causing them to release some juice.
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As the grapes release juice, the carbon dioxide forces the juice to permeate the skins, which triggers fermentation inside the individual grape berries. This is known as intracellular fermentation.
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After a few days, the weight of the grapes at the top of the tank causes the grapes at the bottom to be crushed more fully, releasing more juice.
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The juice at the bottom of the tank, which is now fermenting actively, is drawn off and separated from the remaining whole grapes.
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The juice is then allowed to continue fermenting until it becomes wine. This wine is typically fruity, low in tannins, and has a bright color.
Carbonic maceration was and is often used to produce Beaujolais, but has spread out all over the world. Notably for Cabernet Franc in the Loire, some young Rioja's, Dolcetto in Piemonte and in natural wine pockets all over the world.