Whole Cluster Fermentation

Definition

Whole cluster fermentation (French: vendanges entières, English: whole bunch/cluster fermentation) refers to a winemaking process in which some or all of the grapes are fermented along with their stems (rachis), rather than removing the stems before fermentation. This technique is mainly used in red wine production and is particularly widespread in Burgundy.

The Process

Conventional Red Winemaking

In conventional red winemaking, the harvested grapes are run through a destemmer (égrapoir). This separates the berries from the stems, which are then discarded. Only the berries are fermented along with their skins.

Whole Cluster Fermentation

With whole cluster fermentation, either:

• All grapes are placed entirely with their stems into the fermentation vessel (100% whole cluster)
• A portion of the grapes with stems, and the rest destemmed (e.g. 30–50% whole clusters)

The whole clusters are carefully layered into the fermentation vessel. The lower berries are lightly crushed under the weight of the grapes above, while many berries remain intact.

Two Fermentation Types Proceed in Parallel

With whole cluster fermentation, two different fermentation processes occur simultaneously:

1. Intracellular Fermentation (Carbonic Maceration)

Inside the intact berries, which are surrounded by CO2, anaerobic fermentation within the berry takes place:

• Enzymes within the berry break down malic acid
• Distinctive aromatic compounds are produced
• After several days the berries burst and release their aromatic juice
• This process is similar to the Beaujolais method (macération carbonique)

2. Conventional Alcoholic Fermentation

The juice that has run out from the burst berries ferments normally with yeast. Maceration with skin extraction also takes place here.

The Role of the Stems

The stems (rachis) play a central role and influence the wine in several ways:

Tannins

Stems contain tannins, though of a different quality than tannins from skins and seeds:

• Unripe stems: Astringent, green, bitter – undesirable
• Ripe, woody stems: More refined, spicy, structuring – desirable

The ripeness of the stems is therefore decisive. In cool years or with early harvesting, stems can introduce green, bitter notes. In warm years with a fully ripe harvest they can contribute elegant structure and spice.

Aromatics

Ripe stems bring characteristic aromas:

• Spices: Cinnamon, clove, white pepper
• Herbs: Dried herbs, tea, tobacco
• Floral notes: Violet, fresh flowers
• Peppery character: A hard-to-define "stem spice"

Structure and Aeration

Stems also have physical effects:

• Create air pockets within the must, providing better aeration
• Act as a natural scaffold, loosening the must
• Facilitate pressing after fermentation
• Absorb moisture, slightly increasing concentration

Effects on the Wine

Aromatic Profile

Wines made with whole cluster fermentation typically show:

• More floral notes: Violet, rose, fresh flowers
• Spicy components: Herbs, pepper, exotic spices
• Fresher fruit: Bright red berries, crunchy cherry
• Complexity: Additional aromatic layers

Texture and Structure

• Silkier tannins: Despite extra tannins from the stems, the texture is often finer
• More structure: Vertical, taut structure rather than broad, heavy structure
• Better freshness: A livelier, more tension-filled character
• Elegance: Less opulent, but more finesse-driven

Color

The wines are often somewhat paler in color than fully destemmed wines because:

• The stems absorb a portion of the juice
• Extraction proceeds more gently through the looser must structure

Regional Traditions

Burgundy

The home of whole cluster fermentation. Here the proportion of whole clusters varies depending on:

• Producer: Some use 0%, others up to 100%
• Vintage: More whole clusters in warm years, fewer in cool years
• Vineyard: Old vines with woody stems allow for higher proportions

Renowned estates such as Domaine de la Romanée-Conti traditionally use high proportions of whole clusters.

Rhône

Some producers in the northern Rhône Valley (Côte-Rôtie, Hermitage) experiment with whole clusters for Syrah. The proportion is usually lower than in Burgundy.

New World

Modern Pinot Noir producers worldwide (Oregon, New Zealand, Australia) are increasingly adopting this technique from Burgundy.

Germany

Ambitious German producers of Spätburgunder (Pinot Noir) and Frühburgunder are increasingly using whole cluster fermentation to achieve a Burgundian style.

Prerequisites for Successful Whole Cluster Fermentation

Stem Ripeness

The most important prerequisite: the stems must be physiologically ripe – that is, woody and brown. Green, unripe stems would introduce green, bitter notes. This requires:

• Late harvest
• Healthy grapes
• Good climatic conditions

Suitable Grape Varieties

Particularly well suited are:

• Pinot Noir / Spätburgunder: The classic variety for this technique
• Frühburgunder: Benefits from the additional structure
• Syrah: In certain stylistic directions
• Gamay: For Beaujolais Cru

Less suitable are varieties with naturally very robust tannins or intense color.

Handwork

Whole cluster fermentation requires:

• Hand harvesting: Machine harvesting destroys too many berries
• Careful transport: Intact clusters are important
• Gentle filling: Careful handling in the cellar

Variations and Gradations

The technique is flexible:

• 100% whole clusters: Maximum effect, highest risk
• 50–70% whole clusters: A balanced approach, typical in Burgundy
• 20–30% whole clusters: Subtle influence, the safer option
• 0% (fully destemmed): Modern precision, full fruit expression

Many winemakers vary the proportion depending on the vintage and stem ripeness.

Risks and Challenges

Unripe stems: Lead to green, vegetal aromas and hard, bitter tannins Rot: Rotten or damaged grapes are more problematic with whole cluster fermentation Complexity: More difficult to control than conventional destemming Dilution: Stems absorb juice, slightly reducing yield

Summary

Whole cluster fermentation is a demanding technique that, in the right hands and under optimal conditions, can give red wines additional complexity, finesse, and structure. It requires ripe grapes, healthy fruit, and careful cellar work. The finest examples show how this old Burgundian tradition can produce wines of extraordinary elegance and aromatic depth.