In sherry production, what is flor?

• A. A type of yeast that grows on the surface of the wine in barrel
• B. A grape variety
• C. A chemical additive to stabilize wine
• D. A wine region in Portugal

Answer: (A)

Flor is a living film of yeast that forms on the surface of the wine inside oak barrels during the biologically aged phase of sherry production. This thin layer of yeast creates a distinct environment at the wine–air interface, consuming oxygen and shaping the wine’s chemistry so it stays pale and develops the characteristic fresh, nutty, almond-like aromas associated with Finos and Manzanillas. The flor thrives only within a narrow alcohol range (roughly around 15–16% ABV); when the alcohol climbs too high, the yeast can’t survive and the wine ages oxidatively instead, producing Oloroso. This concept is about a yeast layer, not a grape variety, a chemical additive, or a region, which is why it’s the correct description of flor.