4.2 White Winemaking

White winemaking is designed to produce wine from juice with limited skin contact, preserving freshness and avoiding excessive colour or bitterness — unless the winemaker deliberately seeks texture from skins or oak. Know the sequence cold for SAQs: reception → destem/crush → optional skin contact → press → clarify → AF → rack gross lees → optional MLC / lees ageing → (later maturation and finishing in Chapter 5).

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Reception and Sorting

Grapes arrive and are weighed, sampled (sugar, acid, pH, sanitary state), and often sorted. Sorting removes leaves, unripe or rotten bunches, and MOG (material other than grapes). Hand sorting and optical sorting raise labour/equipment cost and are associated with higher quality and price. Machine-harvested fruit for high-volume whites may receive minimal sorting — faster and cheaper, with higher risk of leaf matter and damaged berries that oxidise and leach phenolics.

SO2 is often added at reception to limit oxidation and wild microbes, especially for aromatic styles. Cool fruit (night harvest or refrigerated trucks) further protects aroma precursors.

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Destemming and Crushing

Most white grapes are destemmed and lightly crushed to release juice without pulverising seeds (seed tannin and bitterness). Whole-bunch pressing (no destem/crush) is used for some premium sparkling bases and delicate whites: gentler extraction, lower phenolics, higher cost and lower yield — a quality signal.

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Skin Contact (Maceration) for Whites

Although whites are juice-driven, brief skin contact (hours, typically cool) can increase aroma compounds and slight texture, used carefully on varieties such as Riesling, Gewürztraminer, or Sauvignon Blanc. Longer contact risks colour, bitterness, and oxidative browning. Orange / skin-contact whites take this to extremes (days–weeks) for tannin and colour — a distinct category, not the default Level 3 “fresh white” path.

Exam cue: “Short cool skin contact before pressing” → modest aroma boost without turning the wine orange.

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Pressing

Juice is separated from skins/seeds in a press. Free-run juice (before heavy pressure) is finer, lower in phenolics, and often reserved for premium lots. Press fractions are richer in phenolics and may be blended carefully, fined more aggressively, or directed to lower-priced wine. Pneumatic presses allow gentle, programmable cycles; harsh pressing raises bitterness and astringency — undesirable in most whites.

Pressing under inert gas or with SO2 protection reduces browning. Hyperoxidation (deliberate oxygen before AF) may be used on non-aromatic varieties to precipitate unstable phenolics; aromatic varieties usually avoid this to protect thiols and terpenes.

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Clarification of Must

Before AF, white must is usually clarified to remove solids (grape particles, dirt) that can create off-flavours or harshness.

Common methods:

• Sedimentation (static settling) — cool must, wait, rack clean juice; gentle and inexpensive; time-consuming
• Flotation — gas bubbles lift solids; faster, suited to larger wineries
• Centrifugation — rapid; capital intensive
• Enzymes — pectolytic enzymes speed settling

Degree of clarification is a style lever: very clean must → pure, clean ferments (good for fresh commercial styles); some solids retained → more texture and complexity but higher risk of reductive notes if mismanaged.

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Alcoholic Fermentation of White Juice

Clarified juice is inoculated (or ferments spontaneously) and ferments off the skins.

Temperature: Cool AF (often ≈12–16°C, sometimes colder for aromatics) retains esters and thiols — passionfruit, grapefruit, floral notes. Warmer AF speeds fermentation and can build weight but loses volatile aroma — more acceptable for neutral varieties destined for oak.

Vessel: Stainless steel dominates for fresh styles. Barrel fermentation (especially Chardonnay) integrates oak and allows gentle oxygen, supporting richer mouthfeel. Concrete eggs may keep fine lees moving for texture without oak flavour.

Yeast choice: Cultured yeast for reliability and specific aroma profiles; wild yeast for complexity and marketing story, with stuck-ferment risk.

Exam scenario: Marlborough-style Sauvignon Blanc — cool stainless AF, protective SO2 regime, no oak, MLC blocked. Burgundy-inspired premium Chardonnay — barrel AF, lees stirring, MLC completed, possible new oak — higher cost, richer style.

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Racking Off Gross Lees

After AF, heavy sediment (gross lees: dead yeast, pulp) settles. Racking transfers wine off this sediment into a clean vessel. Leaving wine too long on dirty gross lees risks reductive or bitter off-flavours. Prompt racking is standard hygiene and quality control.

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Fine Lees and Texture

Fine lees (lighter yeast sediment) can be retained for weeks to months. Autolysis and yeast mannoproteins add body, creaminess, and stability. Bâtonnage (lees stirring) increases contact and texture — classic in barrel-aged Chardonnay. Extended fine-lees ageing raises labour and cellar time → mid to premium pricing. High-volume whites are often racked early and prepared quickly for bottling to free tank space and cut cost.

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MLC Options in White Winemaking

After (or sometimes during) AF, the winemaker decides on malolactic conversion:

• Encourage MLC — fuller whites (many Chardonnays, some Viogniers); softens acid; may add butter/cream (diacetyl); improves microbial stability
• Block MLC — Riesling, Sauvignon Blanc, Albariño, many Pinot Grigios destined for crisp styles; retain malic “bite” and pure fruit

Blocking typically uses SO2 additions, cool storage, and filtration. Partial MLC (blend of MLC and non-MLC lots) is a common premium tool for balance.

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Putting the White Path Together for the Exam

Trace cause → effect:

1. Poor sorting / hot fruit / late SO2 → browning, dull aromatics → lower quality perception
2. Gentle press + cool AF + inert vessel + blocked MLC → pale, aromatic, crisp → classic premium aromatic white recipe
3. Barrel AF + bâtonnage + MLC + new oak → richer, higher cost → Chardonnay template
4. Heavy press fractions blended unchecked → bitterness → quality fault or downgrade to cheaper SKU

Remember: white winemaking cost is driven by fruit quality, sorting, press fractions, oak, lees time, and labour — not by “more steps” alone. A simple stainless path with excellent grapes can outclass a heavily oaked bulk wine on quality while still commanding a fair price for purity and origin.