3.1 White, Rosé & Red Winemaking Processes

White, Rosé & Red Winemaking Processes

Winemaking is the disciplined conversion of fresh grape must into a stable, complex beverage through alcoholic fermentation and precise cellar manipulation. For the Court of Master Sommeliers (CMS) Certified examination, a candidate must demonstrate complete command over the fundamental vinification pathways across white, rosé, and red wines. Every structural attribute evaluated during Deductive Blind Tasting—tannin weight, acid tension, fruit profile, color extraction, and phenolic bitterness—is fundamentally governed by the winemaker's technical choices during harvest, pressing, maceration, and fermentation management.

Harvest & Reception ──> Crushing & Destemming / Whole Cluster ──> Maceration & Pressing ──> Fermentation ──> Maturation

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1. Grape Reception, Sorting & Pre-Fermentation Choices

The physical condition of the harvested fruit dictates the initial cellar pathway:

• Harvest Method & Temperature: Machine harvesting is rapid and cost-effective across flat terrains, but it ruptures berry skins, requiring immediate cooling and sulfur dioxide ($\text{SO}_2$) additions to halt premature wild oxidation and microbial activity. Hand harvesting allows selective picking of whole, unruptured clusters, which is mandatory for sparkling wine production, whole-cluster red fermentation, and botrytized dessert wines.
• Sorting Protocols: Modern sorting spans manual vibrating sorting tables (tapis de tri) to high-speed optical sorters that evaluate individual berry size, color density, and defects via laser optics. Eliminating jacks (stem fragments), green shot berries, and rot-damaged fruit prevents harsh herbaceous pyrazines and oxidative fungal enzymes (laccase).
• Destemming vs. Whole-Cluster Processing:
  • Destemming: Strips berries from herbaceous rachis stems before fermentation, eliminating green, bitter catechins and avoiding stem-derived potassium that can lower must acidity.
  • Whole-Cluster Inclusion: Retaining stems (common in Pinot Noir, Syrah, and Gamay) absorbs anthocyanin pigments (resulting in slightly lighter hue), moderates fermentation heat by providing drainage channels, and contributes savory structural elements like white pepper, black tea, and herbal lift, provided the stems are lignified (brown and woody, not green).
• Sulfur Dioxide ($\text{SO}_2$) Addition: Added at reception (typically 25–50 mg/L) as potassium metabisulfite to function as an antimicrobial agent against wild yeasts (Kloeckera, Brettanomyces) and an antioxidant that denatures polyphenol oxidases (tyrosinase).

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2. White Winemaking Workflow

The fundamental axiom of classic white winemaking is the immediate or rapid separation of juice from grape skins and seeds prior to alcoholic fermentation to prevent the extraction of bitter polyphenols, harsh tannins, and heavy color compounds.

White Grapes ──> (Optional Cold Soak) ──> Pressing ──> Settling (Débourbage) ──> Fermentation (12–18°C) ──> Lees / Vessels

Pressing & Juice Fractionation

• Direct Whole-Cluster Pressing (Pressurage Direct): Grapes are loaded intact into pneumatic bladder presses without prior crushing or destemming. Stems act as natural drainage conduits, permitting gentle juice extraction at lower pressures with minimal solids (bourbes), minimal phenolic pickup, and preserved natural acidity.
• Skin Contact / Cryomaceration (Macération Pelliculaire): For intensely aromatic cultivars (Sauvignon Blanc, Riesling, Gewürztraminer, Viognier), winemakers may allow crushed skins to remain in contact with juice for 4–24 hours at chilled temperatures (4–8°C / 39–46°F) under inert gas (nitrogen or $\text{CO}_2$). This cryomaceration extracts varietal monoterpenes and volatile thiol precursors located in the sub-epidermal skin layers without initiating fermentation.
• Press Fractions:
  • Free-Run Juice (Jus de Goutte / Cuvée): High in malic and tartaric acid, low in pH, clear, low in phenolics and potassium. Represents 60–70% of total juice.
  • Press Juice (Jus de Presse / Taille): Extracted under higher pressure cycles; richer in potassium, higher in pH, higher in suspended solids, darker in color, and more astringent.
• Must Settling (Débourbage): Raw white juice contains suspended pectin, cellular debris, and dirt. It is chilled to 5–10°C in a settling tank for 12–24 hours. Clarified juice (turbidity adjusted to 50–150 NTU) is racked off the sediment (bourbes) before yeast inoculation.

White Wine Fermentation Dynamics

• Temperature Control: Fermented cool, typically between 12°C and 18°C (54°F to 64°F). Low temperatures preserve volatile esters (isoamyl acetate = banana/pear; ethyl hexanoate = green apple/anise) and delicate monoterpenes. Excessive cooling below 10°C risks stuck fermentation, whereas temperatures above 20°C volatilize delicate aromatics.
• Vessel Selection: Neutral stainless steel or concrete preserves crisp primary fruit and sharp linear acidity (e.g., Chablis, Marlborough Sauvignon Blanc, Mosel Riesling). Oak barriques or larger demi-muids encourage micro-oxygenation, textural roundness, and integrated oak spice (e.g., Meursault, Napa Valley Chardonnay, Pessac-Léognan).

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3. Red Winemaking & Cap Management

Red winemaking requires concurrent extraction of anthocyanins (red and purple pigments located in skin vacuoles) and condensed tannins (flavan-3-ol polymers from skins and seeds) during active alcoholic fermentation.

Red Grapes ──> Crushed Must (Juice + Skins + Seeds) ──> Fermentation on Skins (25–32°C) + Cap Management ──> Pressing

The Fermentation Cap (Le Chapeau)

As yeast cells consume glucose and fructose, the generated carbon dioxide gas ($\text{CO}_2$) attaches to grape skins, seeds, and stem fragments, buoying them to the surface to form a dense floating crust called the cap (chapeau). If left unmanaged, the cap dries out, overheats due to trapped metabolic heat, suffers aerobic spoilage by Acetobacter (producing volatile acidity / acetic acid and ethyl acetate), and ceases to yield color and tannin to the fermenting liquid underneath.

Temperature Dynamics in Red Vinification

Red musts are fermented warm, typically between 25°C and 32°C (77°F to 90°F). Elevated temperature increases the solubility of skin tannins and anthocyanins and facilitates the condensation of anthocyanin-tannin polymers, creating stable color that resists oxidative browning. However, exceeding 35°C (95°F) denatures yeast enzymes and causes fatal stuck fermentations.

Pre- and Post-Fermentation Maceration

• Cold Soak (Macération Pré-Fermentaire à Froid): Popularized by Henri Jayer in Burgundy. Must is chilled to 10–14°C for 3–7 days prior to fermentation. In this aqueous, alcohol-free medium, anthocyanins and fruit aromas dissolve rapidly without extracting astringent, alcohol-soluble seed tannins.
• Extended Post-Fermentation Maceration: Leaving new wine on grape skins for 1–4 weeks after fermentation finishes. In this alcoholic medium (13–15% ABV), condensed tannins polymerize into longer molecular chains, shifting perceived tactile astringency toward a smoother, velvety mouthfeel.

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4. Rosé Vinification Methods

Rosé wine production utilizes red grape varieties to create wines possessing the fresh, crisp acidity of white wine combined with delicate red fruit flavors and varying shades of pink, salmon, and ruby.

                         ┌──> Direct Pressing (Presse Directe) ──> Extremely pale pink (Vin Gris)
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Red Grapes (Must) ───────┼──> Short Skin Maceration (6–24 hrs) ──> Deeper pink / coral
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                         └──> Saignée (Bleeding from Red Vat)  ──> Darker, full-bodied rosé

1. Direct Pressing (Presse Directe / Vin Gris):
   • Red grapes are loaded directly into the press (with or without whole clusters) and pressed immediately, exactly like a white wine.
   • The brief contact with skins during the pressing cycle extracts minimal anthocyanins, yielding very pale salmon or onion-skin (pelure d'oignon) colored wines.
   • Benchmark: Classic AOC Côtes de Provence.
2. Short Skin Maceration (Macération Pelliculaire):
   • Red grapes are crushed and allowed to macerate in tank for 6 to 24 hours at cool temperatures until the target color extraction and phenolic grip are attained.
   • Must is pressed off the skins, and the free-run juice ferments as a white wine.
   • Benchmark: AOC Tavel (Southern Rhône), Cerasuolo d'Abruzzo (Italy).
3. Saignée ("Bleeding"):
   • A technique where 10–20% of the pale juice is drawn off ("bled") from a vat of crushed red grapes shortly after crushing (typically 12–24 hours).
   • The primary objective is often to increase the skin-to-juice ratio in the remaining red must to produce a more concentrated, deeply extracted red wine (e.g., Napa Valley Cabernet or Bordeaux).
   • The bled juice is fermented separately into a rosé that is typically darker in color, higher in alcohol, and more robust in structure than direct-pressed rosé.
4. Blending (Assemblage):
   • Mechanically mixing finished white and red wine together.
   • Legal Restriction: Strictly prohibited across European Union Protected Designation of Origin (PDO) still wines. The only major European PDO where blending red and white base wine is legally permitted for rosé production is Champagne AOC (Rosé d'Assemblage).

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5. Carbonic & Semi-Carbonic Maceration

Carbonic maceration is an anaerobic vinification technique that radically alters the traditional fermentation pathway by initiating an intracellular enzymatic fermentation inside whole, uncrushed grape berries prior to any microbial yeast activity.

Whole Intact Clusters ──> CO2-Saturated Sealed Tank ──> Intracellular Fermentation (~2% ABV) ──> Grapes Burst ──> Yeast Finishes

True Carbonic Maceration

1. Sound, whole grape clusters are placed intact into an airtight fermentation vessel.
2. The vessel is completely purged of oxygen and blanketed with industrial carbon dioxide ($\text{CO}_2$).
3. In this strict anaerobic environment, the grape cells switch from respiratory metabolism to anaerobic cellular fermentation (intracellular enzymatic fermentation).
4. Native grape enzymes metabolize intracellular glucose and malic acid into ethanol (reaching approximately 1.5–2.5% ABV), while degrading up to 50% of the grape's natural malic acid without producing lactic acid.
5. During this intracellular process, volatile ester compounds are synthesized at high concentrations, notably isoamyl acetate (banana, candied circus peanuts), ethyl cinnamate (cinnamon, bubblegum), and benzaldehyde (kirsch, maraschino cherry).
6. The grape skins soften, the internal pressure causes berries to burst, releasing sweet juice. The must is pressed off the stems and skins, and inoculated with Saccharomyces cerevisiae to finish alcoholic fermentation in liquid phase at cool temperatures.

Semi-Carbonic Maceration

Semi-carbonic maceration is the standard traditional technique of Beaujolais AOC (Gamay):

• Vats are filled with whole, intact clusters without injecting external $\text{CO}_2$.
• The sheer physical weight of the fruit crushes the bottom 10–20% of grape clusters, releasing juice.
• Ambient or inoculated yeasts initiate conventional alcoholic fermentation in the bottom liquid, releasing large volumes of metabolic $\text{CO}_2$.
• This rising $\text{CO}_2$ gas blankets the upper 80% of intact clusters, establishing an anaerobic chamber that triggers intracellular carbonic maceration in the upper fruit.

Sensory Characteristics of Carbonic Wines

• Color: Vivid, youthful, bright purple-magenta or ruby with electric pink rims.
• Nose: Pronounced, lifted, confectionary aromatics: bubblegum, candied banana, cotton candy, raspberry coulis, and fresh violets.
• Palate: Low, soft, non-astringent tannins (stems and seeds are not extracted under heat and alcohol); lively acidity; light-to-medium body intended for youthful, chilled consumption.

Summary Comparison of Key Vinification Parameters