Wine-making procedure : destemming and crushing

One of the first key stages in the winemaking process

In the world of winemaking, each phase of the process plays a crucial role in defining the final profile of the wine. Of these stages, de-stemming and crushing are particularly significant. These processes, although traditional, have evolved over time, incorporating modern techniques while retaining the basic principles that guarantee the quality and authenticity of the wine.

destemming: separation of berries and stalks

Definition

Destemming is the process by which the grape berries are separated from their stalks, i.e. the woody structure to which they are attached. This operation can be carried out manually or using destemming machines, which automate the process for larger volumes.

Objectives

The main purpose of destemming is to remove the stalks, which are generally rich in tannins and other phenolic compounds that can impart bitter and astringent flavours to the wine. By removing the stalks, the winemaker can control the tannin structure of the wine and avoid excess greenness and bitterness. For certain styles of wine, notably some robust reds, a small amount of stems may be intentionally retained to add complexity and structure.

Destemming techniques

• Manual destemming :
  This is the traditional method used on small estates or for high-quality wines. Although laborious, this technique allows precise control of berry sorting and stalk removal. It is often preferred for delicate grapes that require careful treatment to preserve their aromatic integrity.
• Mechanical destemming :
  This method uses machines that separate the berries from the stalks on a large scale. These machines, equipped with rotating cylinders or beaters, can process large quantities of grapes quickly. The intensity of destemming can be adjusted according to the type of wine desired, allowing either total or partial destemming, depending on whether or not the winemaker wishes to incorporate certain tannins from the stalks.

crushing: crushing the berries to release the must

Definition

Crushing is the action of crushing the grape berries to release the juice (must), which is then fermented. This process can vary in intensity, from very gentle methods that simply open the berries to more vigorous methods that crush the berries to maximise juice extraction.

Objectives

Crushing serves several purposes. Firstly, it initiates contact between the juice and the yeasts present on the grape skins, thus starting alcoholic fermentation. Secondly, it helps to extract the aromatic compounds, colours and flavour precursors contained in the skins, which are essential for giving the wine its unique character. Finally, proper crushing can help regulate the extraction of tannins, influencing the texture and roundness of the wine.

Treading techniques

• Foot crushing :
  Historically, foot crushing was the standard method for crushing grapes. This traditional method is still used in some estates for special cuvées. Foot crushing gently crushes the grapes, preventing the release of bitter tannins from the pips, which is crucial for maintaining the balance and smoothness of the wine.
• Mechanical crushing :
  Mechanical crushing uses crushers that crush the grapes between rollers or under controlled pressures. These machines can be adjusted to modify the intensity of the crushing, allowing the extraction of juices and phenolic compounds to be tailored to the style of wine required.

interaction between destemming and crushing

Destemming and crushing are two stages that can be adjusted independently, but their interaction is essential in determining the character of the wine. Destemming aims to remove the stalks which, although potential sources of tannins and other phenolic compounds, can introduce unwanted vegetal and astringent flavours. Crushing, on the other hand, involves crushing the berries to release the must and the intracellular components that are essential for the wine's colour, aromas and flavours.

Influence of destemming on quality

Full destemming is often sought to produce softer, fruitier wines, particularly for whites and rosés where hard tannins are avoided. However, for certain structured red wines, partial destemming can be beneficial, as the integrated stalks can add complexity and improve the texture of the wine thanks to their natural tannins.

The role of crushing in extraction

If properly controlled, crushing allows targeted extraction of colour and aroma. Too vigorous a crushing, however, can release excessive quantities of tannins and other phenolic compounds from the pips and skins, making the wine hard and less pleasing to the palate. Conversely, insufficient crushing can lead to a lack of depth and complexity in the wine.

strategies for balancing destemming and crushing

The key to optimising the balance between destemming and crushing lies in understanding the specific characteristics of the grapes and the winemaker's stylistic objectives. Here are some of the strategies adopted:

Adaptation to grape varieties

Each grape variety responds differently to de-stemming and crushing methods. For example, grapes with thick, tannin-rich skins may benefit from more intense crushing to extract sufficient colour, while more delicate varieties may require gentler treatment.

Response to annual conditions

Annual climatic variations affect the ripeness and phenolic composition of the grapes. Winemakers need to adjust the levels of destemming and crushing according to the ripeness of the tannins and acidity of the grapes to maintain the quality and balance of the wine from one year to the next.

Use of modern technologies

Technological advances in winemaking equipment allow for precise adjustments to destemming and crushing. Modern machines offer settings that can be fine-tuned to meet the specific needs of each batch of grapes, facilitating better control of the process.

In conclusion, de-stemming and crushing are more than just preliminary steps in wine production; they are fundamental in determining the structure, taste and aroma of the wine. Thanks to technological advances, winemakers today can manipulate these steps with unprecedented precision, enabling them to produce wines that reflect both the unique character of their terroir and their artistic vision. These constantly evolving practices continue to play an essential role in the art of winemaking.

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Note : This article is for information purposes only and does not constitute professional advice. It is recommended that you consult experts and comply with the specific regulations of each industry.

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