Flor (Spanish and Portuguese for ''flower'') in
winemaking, is a film of
yeast on the surface of
wine, important in the manufacture of some styles of
sherry. The flor is formed naturally under certain winemaking conditions, from indigenous yeasts found in the region of
Andalucía
Andalusia (, ; es, Andalucía ) is the southernmost Autonomous communities of Spain, autonomous community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a ...
in southern
Spain. Normally in winemaking, it is essential to keep young wines away from exposure to air by sealing them in airtight barrels, to avoid contamination by
bacteria and yeasts that tend to spoil it. However, in the manufacture of sherries, the slightly porous oak barrels are deliberately filled only about five-sixths full with the young wine, leaving "the space of two fists" empty to allow the flor yeast to take form and the
bung is not completely sealed. The flor favors cooler climates and higher humidity, so the sherries produced in the coastal
Sanlúcar de Barrameda and
El Puerto de Santa María
EL, El or el may refer to:
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* El (deity), a Semitic word for "God"
People
* EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer
* El DeBarge, music artist
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have a thicker cap of flor than those produced inland in
Jerez. The yeast gives the resulting sherry its distinctive fresh taste, with residual flavors of fresh bread. Depending on the development of the wine, it may be aged entirely under the veil of flor to produce a
fino
Fino ("refined" in Spanish) is the driest and palest of the traditional varieties of sherry and Montilla-Moriles fortified wine. They are consumed comparatively young and, unlike the sweeter varieties, should be consumed soon after the bottle ...
or
manzanilla sherry, or it may be fortified to limit the growth of flor and undergo oxidative aging to produce an
amontillado or
oloroso sherry.
During the
fermentation
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...
phase of sherry production, the flor yeast works
anaerobically, converting
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
into ethanol. When all the sugar has been consumed, the physiology of the yeast changes to where it begins an
aerobic process of breaking down and converting the
acids into other compounds such as
acetaldehyde
Acetaldehyde (IUPAC systematic name ethanal) is an organic chemical compound with the formula CH3 CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is a colorless liquid or gas, boiling near room temperature. It is one of the mos ...
. A waxy coating appears on the cells' exterior, causing the yeast to float to the surface and form a protective "blanket" thick enough to shield the wine from
oxygen. This process drastically lowers the acidity of the wine and makes sherry one of the most aldehydic wines in the world. Studies have shown that for the flor to thrive, the wine must stay in a narrow alcohol range of 14.5% to 16%
ABV. Below 14.5% the yeast will not form its protective cap, and so the wine will
oxidize to the point of becoming
vinegar. Above 16% the flor cannot survive, and so the wine essentially becomes an
oloroso.
[Robinson, J. (ed). ''The Oxford Companion to Wine'', Third Edition, Oxford University Press, 2006, pp 664-665. ]
Other regions
A film of yeast similar to flor is also used in the production of
vin jaune in the
Jura wine region in eastern
France. The French term used for this yeast film is ''voile'', meaning "
veil".
A similar yeast to flor is used in the production of ''Szamorodni szaraz'' in the
Tokaj wine region in northeastern
Hungary. The Hungarian name for this yeast is ''hártya'' which means ''film''.
Natural yeast film was traditionally used in
Gose beer to seal bottles, instead of caps or corks.
Flor is also present in some
Vernaccia di Oristano D.O.C. a wine from the italian region of
Sardinia.
See also
*
Yeast in winemaking
References
{{reflist
External links
Flor, the mystery of sherry
Oenology