Concept card Process
Carbonic maceration
In one sentence
A way of making wine in which whole, intact bunches kept under carbon dioxide begin to ferment inside the berry itself.
A vat in semi-carbonic maceration
Carbon dioxide
Given off by the fermentation below, it keeps the bunches away from oxygen.
Whole bunches
Intact, they ferment inside the berry, driven by the grape's own enzymes.
Crushed berries
Crushed by the weight above, they release juice that yeasts ferment.
Key points
- Deprived of oxygen, the berry ferments through its own enzymes, with no yeast and without being crushed.
- Inside the berry, alcohol tops out at 0.5 to 2.2% abv; the wine finishes fermenting after pressing.
- The full form, with no free juice at all, is hard to maintain: semi-carbonic maceration is what is mostly done.
- Semi-carbonic maceration has become the dominant practice in Beaujolais, with Gamay.
- First trials in 1934, by Michel Flanzy, at the oenological station in Narbonne.
What it changes in the glass
- Often a banana note, born of the fermentation, that fades within a few months.
- Sometimes notes of kirsch, strawberry or cinnamon, born of the fermentation inside the berry.
- Pronounced fruit, but in a narrow register: not simply "fruitier" than a conventional red.
Not to be confused with…
The berry also breaks down malic acid, but makes no lactic acid; malolactic fermentation is the work of a bacterium.
A grower wants full carbonic maceration, with no free juice at all. What must they avoid?
One question to test yourself: it does not count towards your progress.
What happens inside the berry
Whole, intact bunches, with no free juice, go into a vat saturated with carbon dioxide. Cut off from oxygen, the grape's cells, still alive, switch from respiration to a fermentative metabolism: fermentation starts inside the berry, with no yeast and no crushing.
The grape's own enzymes do the work. They turn part of the sugar into alcohol and carbon dioxide, and break down part of the malic acid, without making any lactic acid.
0.5 to 2.2% abv
of alcohol in the berry: the alcohol that builds up ends the reaction
Full or semi-carbonic
- Full: nothing but whole bunches, without a drop of free juice. Hard to maintain beyond very small batches.
- Semi-carbonic: the weight of the bunches crushes the berries at the bottom, and their juice ferments with yeast.
- Above, the intact berries ferment from within, shielded by the gas given off by the fermentation below.
- At pressing, the two come together: the wine finishes fermenting the conventional way.
- In Beaujolais, it is mostly the semi-carbonic version that is practised.
Where the aromas come from
None of these aromas is guaranteed: banana is common and fades within a few months; kirsch, strawberry or cinnamon only appear sometimes. Here is where they come from.
- Banana: isoamyl acetate, a fermentation ester favoured by low temperatures and by the conditions of carbonic maceration.
- Kirsch, cherry stone: benzaldehyde, which the intact berry forms from shikimic acid.
- Strawberry, cinnamon: ethyl cinnamate, from the same pathway.
- Hexyl acetate, by contrast, forms during crushing when oxygen is present, and is scarcer here: the fruit is not simply more intense, it shifts register.
A little history
Michel Flanzy ran the first trials in 1934, at the oenological station in Narbonne, so the technique does not date from the 1980s. Over the following decades, semi-carbonic maceration became the dominant practice in Beaujolais, with Gamay.
1934
first trials, at the oenological station in Narbonne
Related reading
Sources (5)
- Reference bookHandbook of Enology, Volume 1: The Microbiology of Wine and Vinifications— Wiley
- Academic publicationAsk the AWRI — Carbonic maceration— Australian Wine Research Institute (AWRI), in Grapegrower & Winemaker
- Academic publicationModification of a Standardized System of Wine Aroma Terminology— American Journal of Enology and Viticulture
- Reference bookThe Oxford Companion to Wine— Oxford University Press
- Academic publicationQuantitation and Sensory Studies of Character Impact Odorants of Different White Wine Varieties— Journal of Agricultural and Food Chemistry