Flor (Spanish and Portuguese for ''flower'') in
winemaking
Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and ...
, is a film of
yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
on the surface of
wine
Wine is an alcoholic drink typically made from Fermentation in winemaking, fermented grapes. Yeast in winemaking, Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different ...
, 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 community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a "historical nationality". The ...
in southern
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = '' Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, ...
. 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
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...
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:
Religion
* 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 or
manzanilla sherry, or it may be fortified to limit the growth of flor and undergo oxidative aging to produce an
amontillado
Amontillado () is a variety of sherry wine characterised by being darker than fino but lighter than oloroso. It is named after the Montilla region of Spain, where the style originated in the 18th century, although the name "Amontillado" is some ...
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 p ...
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 do ...
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 ...
. 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
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...
. 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
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
to the point of becoming
vinegar
Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. Vinegar typically contains 5–8% acetic acid by volume. Usually, the acetic acid is produced by a double fermentation, converting simple sugars to eth ...
. 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
''Vin jaune'' ( French for "yellow wine") is a special and characteristic type of white wine made in the Jura region in eastern France. It is similar to dry fino Sherry and gets its character from being matured in a barrel under a film of yeas ...
in the
Jura wine region in eastern
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
. The French term used for this yeast film is ''voile'', meaning "
veil
A veil is an article of clothing or hanging cloth that is intended to cover some part of the head or face, or an object of some significance. Veiling has a long history in European, Asian, and African societies. The practice has been prominent ...
".
A similar yeast to flor is used in the production of ''Szamorodni szaraz'' in the
Tokaj
Tokaj () is a historical town in Borsod-Abaúj-Zemplén county, Northern Hungary, 54 kilometers from county capital Miskolc. It is the centre of the Tokaj-Hegyalja wine district where Tokaji wine is produced.
History
The wine-growing are ...
wine region in northeastern
Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Cr ...
. 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
Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label= Algherese and Catalan) is the second-largest island in the Mediterranean Sea, aft ...
.
See also
*
Yeast in winemaking
References
{{reflist
External links
Flor, the mystery of sherry
Oenology