Flor Was Once Regarded as a Defect

Yeast has been around for ever and the genus Saccharomyces Cerevisiae has always been responsible for the fermentation of grape juice into wine. It is also responsible for beer (hence "cerevisiae") and bread. Normally after fermentation the alcoholic strength of wine is too much for the yeast and it dies, falling to the bottom of the vessel forming the lees. In the Marco de Jerez however, certain strains of Cerevisiae have discovered the nutritional qualities of the fermented wine (ethyl alcohol, volatile acidity and glycerine, as opposed to sugar) and have evolved the capacity to make the most of it by developing a protective film which allows them to float to the surface forming the veil known as the "velo de flor" responsible for biological ageing.

Among the by-products of yeast metabolisation of components in the wine are those aromas and flavours caused by aldehydes and esters which are so prized today, but this was not the case until well into the XIX century. Until then winemaking was not very scientific and results were unpredictable so flor was seen as an undesirable scum, usually mistaken for Mycoderma Vini, an undesirable (non Cerevisiae) yeast which makes the wine turbid and smelly. If a butt of Fino with flor appeared in a parcel of wine at a bodega, it was duly sent back and the money refunded without question. In fact in ancient times dried flowers were added to the fermentation to improve the wine´s aroma.

Flor through the bunghole, not always pristine white

Gradually, experience showed winemakers that flor, which is not always the pristine white seen in photographs since its appearance varies according to the predominant yeast subspecies and the age of the wine, was not harmful and they came to recognise its beneficial effects on the wine, but it was kept as a trade secret as there was no scientific explanation for it and the scientific community of the day regarded it in a negative light. Undesired flor could of course be got rid of in a variety of ways: topping up the fill level of the butts to leave no headspace, turning the wine to vinegar, distilling, or fortifying it.

Both the solera system and the tradition of ageing under flor (biological ageing) originated in Sanlúcar in the XVIII century with the Vinos Blancos and Manzanillas, while the earliest records of Fino as we know it date back to the beginning of the 1820s. At about this time Sandeman, who at the time were UK agents for Pemartín, wrote to tell them that tastes were now for lighter, paler wines. It is worth noting however that not all such wines were actually Fino, and some were blends of mosto and Fino, with small additions of alcohol and sweet wine for the British taste.

The more public image of flor

But biologically aged wines had their proponents who saw them as a potentially profitable line, especially as the large British market was looking for a lighter style of wine. After all, if the wine tasted good there can´t have been much wrong with it and the flor protected it from oxidation, keeping it pale and fresh. William Garvey had faith in Fino but at first had to work with it at night for fear of being laughed at by other bodegueros. He began exporting it in a very small way in the 1820s and Fino San Patricio in a serious way from the 1850s, while González Dubosq (later González Byass) began exporting Tio Pepe in quantity in 1844 and Wisdom & Warter in the 1850s. Bodegas began to be constructed on a larger scale which would give flor the ideal environmental conditions and Fino was thus recognised as a style of Sherry in its own right, long before science had figured out what it actually was.

It was only in the 1930s that microbiological researchers managed to identify flor as consisting of Saccharomyces Cerevisiae as distinct from Mycoderma Vini, and from that point on it was seen in a much more positive light than the mere “organisms” of before. And it was as recently as the 1970s that the sub-species of Cerevisiae (S Beticus, S Cherensiensis, S Montuliensis and S Rouxii) and their effects on the veil of flor were identified. So biologically aged wine has gone from being “weak”, “sick” and “defective” to a unique oenological treasure in a fairly short period of time, with combined global sales now amounting to almost half of all Sherry sales.