Carbonic maceration

Carbonic maceration is whole-berry work. Tesniere and Flanzy: intact clusters go into a closed tank already rich in carbon dioxide. Inside each sound berry, metabolism flips from respiration to anaerobic, intracellular fermentation without yeast in the flesh. Grape enzymes do a little of yeast’s job first. Yeast then work in the juice that collects at the bottom from berries that crushed under their own weight. After that first “maceration–fermentation,” the free juice is drawn, the fruit is pressed, and a second fermentation — alcoholic, then typically malolactic — finishes the wine ¹.

That is not crushed-cap Extraction. Crushed Must puts skins in a liquid ferment from the start; tannin and color move with alcohol as Smith describes for ordinary red ferments ². Here the berry stays a living cell as long as its skin holds. Harvest and handling have to keep berries intact; rough fruit is the wrong raw material ¹. An AVA does not prescribe the method ³.

What the berry does under CO₂ #

Under atmospheres they treat as under 1 percent oxygen, ripe Vitis vinifera berries run fermentative metabolism. The chapter’s abstract: a small conversion of sugar to alcohol (about 1.5–2 percent alcohol inside that intracellular phase), malic acid reduced by about half, and secondary products (they name glycerol and acetaldehyde among them) ¹. Those figures are Tesniere and Flanzy’s, not a house recipe. The grape’s own alcohol dehydrogenase is what lets the intact berry make ethanol; that is still not Wine fermentation by Saccharomyces in the tank juice.

Four steps in that chapter: (1) vat intact, healthy clusters in CO₂, (2) maceration–fermentation with some fruit in gas and some in the forming liquid, (3) run off and Pressing wine, (4) the second ferment, including Malolactic fermentation ¹. Shared biology with other ferments is Fermentation; the vessel and atmosphere determine the sequence.

Color and Tannin in carbonic wines depend strongly on time and temperature of that first step in their account. They also note density, dry extract, fixed acidity, and residual sugar often read lower than in wines from crushed grapes — a comparison from that review, not a tasting-bar law ¹. Do not copy their “superior quality” as a fact.

What to notice #

Look: whole clusters, a tank blanketed in gas, a growing puddle of juice, skins that have not been punched into a cap the way a crushed red is. Smell: the distinctive fruit associated with the method, without treating one aroma compound as a diagnostic. Taste: often softer acid if malic dropped in the berry, and a tannin feel that is not the same as a long pumped-over cap — still taste structure, not slogans.

Failure: crushed or rotten fruit claimed as carbonic. Failure: skipping the yeast ferment in the free-run and calling intracellular ethanol “the wine.” Failure: treating this as extraction-by-another-name.

Grape has to arrive whole. Return to Wine.