Destemming vs. Whole Cluster Retention — Philosophy & Effect

Destemming is the mechanical separation of grape berries from the rachis before fermentation, most commonly performed using a destemmer-crusher machine. Whole cluster fermentation retains the entire grape bunch, including berries, stems, and all, during primary fermentation. The technique is also called stem inclusion or whole bunch vinification. Between these two poles lies a wide spectrum: winemakers frequently blend proportions of whole cluster and destemmed fruit, either in the same vessel or fermented separately and blended later, to achieve targeted tannin and aromatic profiles.

• Destemmed fruit ferments on skins and seeds only; stem phenolics are excluded entirely
• Whole cluster fermentation can encourage semi-carbonic activity within intact berries, producing lifted aromatic esters
• Partial stem inclusion (commonly 20-50%) is a common middle path for complexity without excessive herbaceousness
• Fermentation kinetics differ: whole cluster lots tend toward cooler temperatures and slower cap formation than fully destemmed ferments

Stems are rich in polyphenolic compounds, particularly condensed tannins (proanthocyanidins), phenolic acids, and flavonols including quercetin glycosides. When stems are present during fermentation, potassium leaches from the rachis into the must, binding with tartaric acid, which lowers titratable acidity and raises pH. This pH increase can reduce anthocyanin stability and limit color extraction, which is why whole cluster wines are sometimes lighter in color when young, though some research suggests color stability may improve over time as anthocyanins bind with stem-derived tannins. Green stems release elevated concentrations of methoxypyrazines, adding unwanted vegetal notes; fully lignified stems contribute more refined phenolic character.

• Potassium from stems binds tartaric acid, raising pH and reducing titratable acidity
• Stems contain condensed tannins built on epicatechin and catechin subunits, similar in composition to skin tannins
• Higher pH can reduce anthocyanin extraction and early color intensity
• Methoxypyrazine concentrations increase significantly with stem inclusion, especially from unripe rachis tissue

Destemmed wines emphasize purity of fruit, with cleaner red and black fruit character, less noticeable tannin, and a more accessible, fruit-forward profile at a younger age. Whole cluster wines typically display greater structural complexity, with spice notes ranging from white pepper and clove when stems are ripe to green peppercorn and rosemary when less so, alongside a drying, gripping tannin quality that proponents describe as providing backbone and length. Partial stem inclusion threads the needle, contributing textural lift and aromatic dimension without overwhelming the fruit. Winemakers widely note that ripe stems produce silky, integrating tannins, while underripe stems can leave harsh, green-edged astringency.

• Destemmed lots: higher peak fermentation temperatures, more purity of red fruit, less noticeable tannin
• Whole cluster lots: spicy, lightly pyrazine-influenced aromatics, more pronounced and drying tannin structure
• Ripe stems add clove, cedar, and forest floor complexity; unripe stems add green peppercorn and herbaceous notes
• Whole cluster Pinot Noir can gain useful body and tannin, especially in cooler vintages where the fruit is lighter in color and texture

The decision to include stems hinges primarily on stem ripeness, assessed by tasting and visual inspection of the rachis. In cool or wet vintages, stems often remain green and rubbery, making destemming the safer path to avoid vegetal faults. In warm, ripe vintages where stems lignify fully to a brown, woody state, whole cluster fermentation becomes a powerful tool for structure and aromatic complexity. Burgundian producers adjust their stem percentage annually: in ripe years such as 2005, 2009, and 2015, many producers increase whole cluster use, while cooler or wetter years call for more destemming or full destemming. Bordeaux varieties, which carry naturally higher pyrazine levels, are almost always fully destemmed to avoid compounding herbaceous character.

• Cool vintage with green stems: destem fully to prevent vegetal and herbaceous fault
• Warm vintage with lignified, brown stems: whole cluster use can add structure and aromatic complexity
• Bordeaux varieties (Cabernet, Merlot) rarely ferment with whole clusters due to elevated natural pyrazine levels
• Climate change is increasing stem ripeness in Burgundy, making whole cluster a more viable tool than in previous decades

Burgundy is the heartland of the whole cluster debate. Domaine de la Romanée-Conti uses whole clusters as their standard practice, with approximately 25-30% destemming in typical vintages and near-100% whole cluster in exceptional years like 2015. Domaine Dujac, led by Jeremy Seysses, is known for 65-100% whole cluster across its cuvées. The late Henri Jayer, by contrast, was a fervent advocate of complete destemming and influenced a generation of producers toward that style. In the Northern Rhône, practices vary by producer and cuvée: Guigal determines destemming based on harvest-time ripeness assessment, with La Landonne typically receiving little or no destemming while La Mouline and La Turque are largely destemmed. In Beaujolais, whole cluster carbonic maceration is the traditional method for Gamay. New World producers are split, with some Oregon Pinot Noir producers embracing whole cluster and most Napa Cabernet producers preferring full destemming.

• Domaine de la Romanée-Conti: whole clusters as standard, with about 25-30% destemming in most vintages, near 100% whole cluster in top ripe years
• Domaine Dujac: 65-100% whole cluster, citing silkier tannins and spicy complexity
• Henri Jayer: famously opposed to stems, influencing many Burgundian producers toward full destemming
• Bordeaux Right Bank and most Napa Valley producers: predominantly destem for fruit clarity and consistent phenolic management

Contemporary winemakers increasingly favor separate fermentations of whole cluster and destemmed lots rather than mixing them in the same vat. Keeping them apart preserves the distinct aromatic and textural voices of each approach, allowing post-fermentation blending decisions based on sensory evaluation. Optical sorting technology enables real-time assessment of stem and berry quality, helping winemakers reject underripe or compromised material. Some producers experiment with air-drying removed stems before adding them back to fermenting wine, theoretically polymerizing stem tannins in advance to reduce their reactivity and oxidize green aromas. Temperature management is also critical: whole cluster lots favor cooler fermentations that preserve aromatic purity, while destemmed lots tolerate warmer temperatures that build body.

• Separate fermentation of whole cluster and destemmed lots preserves distinct aromatic and textural profiles for later blending
• Optical sorting allows evaluation of stem and berry ripeness in real time, improving selection rigor
• Air-drying stems before reintroduction is an emerging experimental technique to reduce astringency and green character
• Whole cluster fermentation favors cooler temperatures; destemmed lots favor warmer fermentations and fuller body