Destemming is the process of separating grape berries from the stems, or rachis, before or during winemaking. It is commonly performed with a mechanical destemmer, often combined with a crusher. Destemming reduces the amount of stem material in the fermentation vessel, which can influence tannin, flavour, fermentation dynamics and the structure of the finished wine.
Stems contain tannins and other phenolic compounds. If stems are unripe or green, they can contribute harsh, bitter or vegetal character. Removing them allows the winemaker to control how much stem material is included. Ripe stems may be retained intentionally in whole-cluster or partial whole-bunch fermentations to add structure, spice or aromatic complexity.
Grape bunches pass through a machine that separates berries from the central stem structure. The berries may then be gently crushed or transferred whole to the fermentation vessel. Machine settings and handling are adjusted to minimise damage to berries and seeds.
Destemming removes the stems. Whole-cluster fermentation retains some or all of the stems with the berries. Some producers use a partial whole-cluster approach, combining destemmed fruit with intact bunches to achieve a particular balance of fruit, spice and tannin.
Example: a Bordeaux producer may destem Cabernet Sauvignon before fermentation, while a Burgundy producer may retain a portion of ripe stems in a Pinot Noir fermentation.
Chef’s note: destemming is a technical choice, not a universal rule. Stem maturity and the desired wine style determine whether stems are removed or retained.
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