Growing the Vines
Wine begins in the vineyard, where grapevines follow an annual cycle. Budburst arrives in spring, followed by flowering and fruit set. Throughout summer, shoots grow, leaves photosynthesise, and grapes develop. Late summer brings véraison, when grapes change colour and accumulate sugar. Harvest timing is critical: pick too early and fruit lacks ripeness; too late and acidity plummets whilst sugar soars.
A single vineyard block might be harvested over several passes, selecting only the ripest fruit for premium wine. Some producers deliberately leave grapes on the vine longer, concentrating sugars for sweeter styles or higher alcohol.
Harvest
Harvest can be mechanical (high-speed mechanical harvesters shake vines, allowing fruit to fall onto conveyers) or hand-harvested (workers pick grapes individually into small bins). Hand harvesting costs far more but allows selective picking, rejecting unripe or damaged fruit. Premium producers almost always hand-harvest.
For white wine, grapes are usually pressed immediately after harvest, separating juice from skins. For red wine, grapes are destemmed (separating berries from woody stems) and crushed, beginning the crucial skin contact that colours the wine. The crushed grape mass—called must—ferments with skins present.
Fermentation
Fermentation is the heart of winemaking. Wild yeasts naturally present on grape skins, or cultured yeast added by the winemaker, convert grape sugars into alcohol and carbon dioxide. A 12% alcohol wine requires roughly 2% residual sugar to ferment to dryness. Temperature control is essential: cool fermentation (12–16°C) preserves delicate aromas but takes weeks; warm fermentation (18–25°C) proceeds quickly but loses aromatic complexity.
During red wine fermentation, skins naturally rise, forming a "cap." Winemakers manage this cap through punching down (pushing solids back into liquid) or pump-over (pumping liquid over the cap) to ensure full colour and tannin extraction.
Following primary fermentation, many wines undergo malolactic fermentation, where naturally occurring bacteria convert sharp malic acid (found in unripe apples) into softer lactic acid (found in milk and cheese). This softens acidity and adds buttery, creamy notes—essential in fine red wines and common in Chardonnay.
Ageing and Maturation
After fermentation, wine rests and matures. Many fine wines spend time in oak barrels, typically 225-litre Bordeaux barrels or slightly larger Burgundy puncheons. New oak imparts vanilla, spice, and toast; older barrels contribute more subtle oak influence. French oak is finer-grained and more refined; American oak offers bolder vanilla and coconut. Top Burgundy and Bordeaux spend 18–24 months in barrel, developing complexity and colour stability.
During barrel ageing, wine slowly oxidises, polymerising tannins and developing secondary flavours—the earthy, mushroomy notes of aged red wine or the honey and toast of aged white wine. Some wines spend months on their lees (dead yeast cells), which adds richness and complexity.
Inexpensive wines might skip barrel entirely, resting in stainless steel or concrete for a few months before bottling. Premium producers believe extended contact with wood and oxygen develops essential structure and ageing potential.
Fining, Filtration and Bottling
Before bottling, wine must be clarified—tiny particles suspended in liquid make it cloudy. Fining uses natural substances to bind particles and make them settle. Bentonite (powdered clay) is common; egg whites are traditional in Burgundy; some producers use isinglass (fish bladder). Most fining agents are removed before bottling, though traces remain.
Filtration physically strains particles from wine using paper or membrane filters. Sterile filtration removes even yeast and bacteria, stabilising wine and preventing unwanted fermentation in bottle. However, aggressive filtration can strip aromatic compounds. Many premium producers now prefer natural, unfiltered wines, accepting some haze for maximum flavour complexity.
Finally, wine is bottled, typically in glass to prevent oxygen ingress. Most wines receive a small amount of sulphur dioxide (SO₂) before bottling—a natural preservative that prevents oxidation and microbial spoilage. Quality wines rest for 6–12 months in bottle after release before reaching peak drinkability.
How Sparkling Wine is Made
Sparkling wine begins like still wine—fermentation of base wine. But additional steps create its bubbles. In the traditional method (Champagne method), a mixture of yeast and sugar is added to finished wine, then sealed in bottle. Yeast ferments the sugar, producing alcohol and carbon dioxide trapped in bottle—the bubbles. After 18 months to several years, dead yeast cells (lees) accumulate on the bottle's side.
Riddling—gradually tilting bottles neck-down over weeks—slides lees towards the cork. The neck is then frozen, the cork popped, and the frozen plug of lees ejected (disgorgement). A small amount of sugar syrup (dosage) replaces lost wine, determining final sweetness: Brut (dry, 0–12g/L sugar) is most common.
The Charmat method (used for Prosecco) ferments wine in large pressurised tanks, capturing CO₂ efficiently and cheaply. It produces fresher, fruitier wines but lacks complexity; no extended lees contact means less development. Each method produces valid sparkling wine; Champagne's prestige partly reflects its labour-intensive traditional method.