Aged Under Flor
Flor is the Spanish or Portuguese word for flower. In wine terms, flor refers to a layer or film of yeast that forms on the surface of wines after alcoholic fermentation, under certain winemaking conditions.
When these yeast cells coalesce to form a continuous layer on the top of the wine, they create a protective barrier that inhibits oxygen exposure. This phenomenon is referred to as biological ageing.
Fino style Sherries are famous for their maturation under flor. Vin Jaune from the Jura region in France is another well-known example of wine aged sous voile (a French term which means, under a veil) – although here, the yeast layer is often thinner and not totally hermetic.
Wines aged under an unbroken layer of flor will be very pale in colour with fresh acidity and youthful vibrancy. Where the flor layer is not continuous, as is often the case with the voile in Vin Jaune, this effect is negated.
As it consumes the alcohol in wine, the flor yeast produces acetaldehyde. This compound gives off distinctive bruised apple and nutty aromas.
The flor yeasts also feed off the wine’s glycerol. As glycerol diminishes, the round, smooth mouthfeel of a wine diminishes making it far lighter and somewhat sharper on the palate.
Flor yeast activity also leads to the increase of an aromatic compound called sotolon. At low levels, sotolon gives notes of maple syrup or caramel. At high concentrations, it gives off exotic spice aromas like curry or fenugreek.
