Fermentation on the skins is the central process in red wine production. Learn how color, tannins, and aromas are extracted from grape skins.
Fermentation on the skins (German: Maischegärung) refers to the fermentation process in which the must ferments together with the solid grape components (skins, seeds, and sometimes stems). This process is characteristic of red wine production and is decisive for the development of color, tannin structure, and the aromatic spectrum.
After harvest, the grapes are destemmed (stems removed) and lightly crushed or ground. The result is the must mass (Maische) — a mixture of juice, skins, seeds, and possibly stems. This mass is filled into fermentation vessels.
Alcoholic fermentation is triggered by yeasts — either by natural yeasts on the grapes (spontaneous fermentation) or by added cultured yeasts. During fermentation:
The most important substances extracted from the skins during fermentation on the skins:
Color compounds (anthocyanins) are found in the skins of red grapes. Extraction occurs mainly in the first 3–5 days of fermentation. The developing alcohol acts as a solvent and intensifies color extraction.
Tannins come from skins, seeds, and stems (if included). They give the wine structure, aging potential, and the characteristic mouthfeel. Tannin extraction is time-dependent and increases with longer maceration time.
Aromatic compounds from the skins contribute significantly to the flavor profile. Primary fruit aromas, but also more complex notes, are released during fermentation on the skins.
To ensure optimal extraction, the cap must be regularly brought into contact with the fermenting must:
Pigeage (punch-down): A traditional method in which the cap is pushed down mechanically or by hand into the must. This was formerly done by hand with wooden poles, but today is mostly mechanical.
Remontage (pump-over): The must is drawn off from below and pumped over the cap. This method is less oxidative than pigeage and allows for gentler extraction.
Délestage (rack and return): The entire must is drained off, the cap collapses, and the must is then pumped back in. This leads to more intensive extraction and better oxygen uptake.
Fermentation temperature significantly influences extraction:
The maceration time varies depending on the desired wine style:
After fermentation, the wine is separated from the solids — this is called pressing. The free-run must (free-run wine) is usually finer than the press wine obtained by mechanical pressing.
The fundamental difference between red and white wine production lies in the fermentation on the skins:
Red wine: Fermentation with skins (on the skins) → color extraction White wine: Fermentation without skins (juice fermentation) → no color extraction, also possible with red grapes (e.g., Blanc de Noirs)
Exception: Orange wines are white wines made like red wines with fermentation on the skins, which leads to more intense color and tannins.
The type of fermentation on the skins fundamentally shapes the character of the red wine:
Traditional fermentation on the skins in large wooden vats or stainless steel tanks with moderate extraction yields accessible, fruit-forward wines. This is typical of classic German red wines such as Spätburgunder or Frühburgunder.
Modern Burgundian method with whole-cluster fermentation, cold maceration, and extended maceration time produces structured, complex wines with high aging potential.
Mediterranean method with high temperatures and long maceration time creates powerful, tannin-rich wines as in Barolo or Rioja.
Fermentation on the skins is therefore not just a technical process, but a tool with which winemakers can deliberately shape the character of their red wines.
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