The term flor in Sherry refers to:
A. The floral aromas winemakers hope to capture in young Sherries known as Manzanillas
B. The bottom layer of barrels (“on the floor”) that holds the oldest wines in the solera aging system
C. Sherries that are sweetened by blending dry styles of Sherry with sweet wines or grape syrup
D. The film of native yeast cells that forms on the surface of an aging Sherry in barrel
While flor does mean “flower” in Spanish, with regard to Sherry, it refers to the thin layer of native yeast cells that are allowed to “bloom” on top of manzanilla and fino Sherries as they age in casks. Flor acts to prevent oxidation and also contributes a unique tanginess to the wine. In the production of most wines around the world, as the contents of barrels slowly evaporate throughout the aging process, barrels are kept topped up with wine in order to minimize the contact the wine has with air and avoid spoilage organisms. Two traditional practices are necessary to support the development of flor. Firstly, barrels are only filled to four-fifths of their capacity. Secondly, the solera principle of blending various ages of wines is essential, as the regular addition of new wine supplements the transfer of nutrients and keeps the flor thriving. In case the flor dies off (either naturally or intentionally), the sherry will have air contact and is then classified as an Amontillado, will undergo an additional fortification, and continue aging in an oxidative way.