Flor (ageing process)

Flor

Nature's Protective Veil

Ageing under flor is a winemaking technique where a layer of yeast forms on the surface of wine during barrel ageing. This biofilm, known as flor, protects the wine from oxidation while transforming its flavor and texture. The result is a wine that balances freshness with complex savory notes, offering a truly distinctive profile.

The Flor Veil
Flor thrives in specific conditions: moderate alcohol (14–15.5%), cool temperatures, and high humidity. Winemakers leave barrels partially filled to allow oxygen to sustain the flor. The yeast consumes alcohol, glycerol, and acids, producing compounds like acetaldehyde and sotolon, which contribute flavors of green apple, almond, curry, and toasted nuts. Flor also reduces glycerol levels, creating wines with a leaner, lighter mouthfeel. This process preserves the wine’s pale color while imparting briny, umami-rich characteristics.

Regional Expressions
Flor aging is most famously associated with Spain’s Jerez region and France’s Jura. In Jerez, flor defines biologically aged sherries like Fino and Manzanilla, which are fortified to around 15% ABV and aged in partially filled barrels. These wines are bone-dry with saline notes, chamomile aromas, and almond flavors. In Jura, flor aging is used for Vin Jaune, made from Savagnin grapes. Unlike fortified sherry, Vin Jaune ages unfortified for at least six years under flor (sous voile), developing intense flavors of ginger, curry spice, and candied citrus alongside subtle oxidative notes.

To Sum It All Up...
Flor ageing transforms wine into a living expression of yeast and terroir. From the briny elegance of Manzanilla to Jura’s enigmatic Vin Jaune, this ancient technique showcases how microbial activity can create some of the most captivating wines in the world.

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