Wine · Terminology

Flor

The living veil of yeast that grows on Fino Sherry, protecting it from oxygen and making it tangy.

Flor — velo de flor, "veil of flower" — is a film of yeast that grows spontaneously on the surface of Sherry in a part-filled butt. It is a strain of Saccharomyces cerevisiae adapted to live at the wine–air interface, forming a waxy layer several millimetres thick.

The veil does two things at once. It seals the wine from oxygen, keeping it pale and fresh, and it metabolises alcohol, glycerol and acetic acid, producing acetaldehyde — the compound responsible for Fino's distinctive tangy, bruised-apple, almond character. Ageing under flor is called biological ageing.

In practice

  • Flor needs 15–15.5% alcohol: below it other organisms take over, above about 16.5% the yeast dies.
  • The butt is filled to only about five-sixths, leaving deliberate ullage for the veil to breathe.
  • It needs a cool, humid cellar — hence the tall, thick-walled bodegas of Sanlúcar and Jerez.
  • Flor thins in summer and thickens in spring and autumn; in Sanlúcar's damper maritime air it survives year-round, which is what makes Manzanilla distinct from Fino.

Where you'll meet it

  • Jerez and Sanlúcar de Barrameda, in the fortified wine guide.
  • The Jura's Vin Jaune, aged for six years under a similar voile — unfortified.
  • Increasingly, experimental flor-aged wines in Australia and California.

The Sherry styles and their veils

Style Fortified to Flor Character
Fino ~15% Full life under flor Pale, tangy, almond, saline
Manzanilla ~15% Year-round, Sanlúcar Even lighter, markedly saline
Amontillado ~15%, then ~17% Flor first, then dies Amber, hazelnut, dry
Palo Cortado ~15%, veil fails naturally Partial Fino nose, Oloroso body
Oloroso ~17% None — killed at the outset Dark, walnut, rich, dry

The solera

Flor also depends on the solera system: fractional blending through stacked tiers of butts, where wine drawn from the oldest tier is replaced from the next, and so on. Regular refreshment with younger wine feeds the flor the nutrients it needs to survive — without it, the veil would starve.

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