De-stemming

De-stemming is carried usually carried out with a mechanical de-stemmer, where the bunches are passed along the inside of a perforated drum. The perforations are only large enough to let the berries through: the stems are ejected from the other end of the drum.

  Advantages of de-stemming Disdvantages of de-stemming
White wines
  • Stems can release bitter & herbaceous flavours into wine.
  • It allows more fruit to fit into the press (and presses are an expensive bottleneck in the white winemaking process).
  • Other MOG can be removed at de-stemming.
  • A poor de-stemmer will often damage the stems so badly that more bitter & herbaceous flavours are released than if a de-stemmer had not been used.
  • Pressing without the stems is slower as the stems provide drainage channels.
  • De-stemming is not appropriate for vintages destined for sparkling wines.
Red wines
  • Stems can release bitter & herbaceous flavours into wine.
  • Stems release water and potassium and absorb colour and alcohol.
  • The presence of stems will reduce compaction of the cap of pomace in the tank and make temperature control and phenolic extraction easier.
  • In some varieties, the stems can release good quality tannins which improve mouthfeel, stabilise colour and reduce the damage done by oxidation.
  • De-stemming is not appropriate for vintages destined to undergo carbonic maceration (e.g. Beaujolais Nouveau)

Machine harvested fruit does not normally need de-stemming, except to remove MOG.