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Destemming

From Vinopedia

Destemming refers to the removal of grape stems from harvested bunches prior to or during the initial stages of winemaking. The process, also known as de-stalking, is carried out to separate the berries from the lignified stalk structure, which contains tannins and other phenolic compounds that can influence wine character if extracted[1]. In modern wineries, destemming is most commonly achieved using mechanical equipment, although manual methods are still employed in certain artisanal or small-scale contexts[2].

Background

In traditional winemaking, grapes were often fermented with their stems intact, a practice that could enhance tannic structure but also introduce green or herbaceous flavours if the stems were insufficiently lignified[3]. The advent of mechanical destemmers in the 20th century allowed winemakers to selectively remove stems, giving greater control over tannin management and mouthfeel[4]. Modern equipment enables precise adjustment of the degree of destemming, ranging from complete removal to partial retention for stylistic purposes.

Process and techniques

Destemming is typically performed immediately after harvesting and sorting, before the grapes are crushed. The operation separates the berries from the central stem or rachis, which consists of lignified tissue and can impart bitterness if fermented in large quantities[5]. Mechanical destemmers use rotating cages and paddles to dislodge berries, with the gap size and speed adjustable to control the level of separation[6]. In some artisanal or small-scale operations, destemming is performed by hand, which can be gentler on delicate varieties and reduce berry damage. Partial destemming may be employed when winemakers wish to retain some stem influence for added tannin or aromatic complexity, particularly in varieties such as Syrah or Pinot Noir.

Impact on wine style

The decision to destem fully, partially, or not at all has a marked effect on the resulting wine’s structure and aromatic profile. Complete destemming generally produces wines with softer tannins and a purer fruit character, as stems can contribute harsher phenolic compounds and a green, herbal note if insufficiently lignified[7]. Partial or whole-bunch fermentation, in contrast, can introduce additional tannin, enhance aromatic complexity, and modify fermentation kinetics by improving juice drainage and aeration[8]. These effects are especially valued in certain traditional wine styles, though they require careful assessment of stem maturity to avoid unwanted bitterness or astringency.

See also

References

  1. ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, ISBN 978-0198705383.
  2. ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020, ISBN 978-0128161180.
  3. ↑ Peynaud, The Taste of Wine: The Art and Science of Wine Appreciation, Wiley, 1996, ISBN 978-0471113769.
  4. ↑ Hidalgo Togores, Tratado de Viticultura, Mundi-Prensa, 2002, ISBN 978-8484761743.
  5. ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020, ISBN 978-0128161180.
  6. ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015, ISBN 978-0198705383.
  7. ↑ Peynaud, The Taste of Wine: The Art and Science of Wine Appreciation, Wiley, 1996, ISBN 978-0471113769.
  8. ↑ Hidalgo Togores, Tratado de Viticultura, Mundi-Prensa, 2002, ISBN 978-8484761743.
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