Fascinated By Flor

I’ve become fascinated by flor. And I’m not the only one by the looks of things. While I’m not suggesting that the only rational explanation for the surge in popularity of sherry and wines from the Jura is attributable to the velum of yeast that grows on the surface of these wines, it surely can’t be mere coincidence that so many wine hipsters have chosen these two as their rallying call. Anyone for a glass of Vernaccia di Oristano?

Always up for a bit of wine-geekery, I’ve taken to passing airmiles by reading academic journals and publications on the ecology and population dynamics of flor yeasts. This has had two immediate effects – a steady stream of good natured abuse on social media, and a realisation of how little I really know about flor. One of the more interesting publications I’ve come across is “Investigations Of The Flor Sherry Process” by W.V. Cures, who in 1947/1948 sought to evaluate whether flor yeasts and the principle of the solera system of ageing were adaptable for use in California wineries. Frustratingly, as with most academic literature, outcomes reached by one research group are often disproved by others.

The conclusion reached by Esteve-Zarzoso et al. (2001) that the yeast population dynamics during biological ageing is a complex phenomenon, and that differences can be observed between yeast populations in different wineries seems intuitive. Less obvious to many will be their assertion that there are two different populations of S. cerevisiae strains conducting the elaboration of fino sherry wine, one responsible for fermentation and the other responsible for velum formation. Julian Jeffs, in his book ‘Sherry’, notes that “unlike those which affect fermentation, the yeast cells of the flor function in aerobic phase” with four identified in all: S. beticus, S. cheresiensis, S. montuliensis, and S. rouxii. However, as highlighted in a review conducted by Alexandre (2013) S. beticus and S. cheresiensis are no longer considered as races or subspecies of S. cerevisiae and according to the study by Kurtzman et al, (2011) and S. montuliensis is now considered as Torulaspora delbrueckii, whereas S. rouxxi is now classified as Zygosaccharomyces rouxii.

Confused yet?

Management of flor within a bodega is critical and the conditions under which flor develops and is maintained are well outlined by Peter Liem and Jesús Barquín in their book ‘Sherry, Manzanilla and Montilla’. The composition of yeasts within the velum of flor differs depending on environmental conditions and different combinations will have a different effect on the wine. In their book ‘Manzanilla’ Christopher Fielden and Javier Hidalgo note that “in Sanlúcar it is just one strain, cheresiensis, that predominates” while also suggesting that flor appeared for the first time at the end of the 18th / first half of the 19th centuries, this in turn lead to the creation of the solera system and that these happened in Sanlúcar, before the rest of the region.

Javier Hidalgo has remarked that flor grows more strongly in butts on the side of the bodega near the sea than in those on the sides nearer the town. While it’s also widely known that relative proportion of the various strains alters as the wine progresses through the solera, it’s the supposedly random variance within a bodega or solera itself that really interests me and is further explored in Alexander Jules’ Fino 4/65.


This fino is a selection of 4 of a 65 barrel solera from bodega San Francisco Javier of Juan Piñero in Jerez. The solera of only 3 criaderas started in 1940 and is refreshed by from wine from Pagos Macharnudo and Añina.

Alex Russan, the man behind the Alexander Jules sherries, notes that in this solera there are “a handful of barrels which, at random, have become dominated by the Sacchromyces montulienses strain, which gives very pungent aromatics (it produces much higher levels of Fino’s hallmark acetaldehyde compound), and has a greyer, patchier layer of flor on top of the wine.” Three of these barrels were selected for this May 2015 release, with the fourth barrel dominated by the more common S. beticus.

The sherry is hugely pungent with bright floral aromatics with hints of orange blossom. It’s intense and starts with an oily citrus and broad yeasty character on the palate culminating in a long briney finish. This is a large scaled fino which seems to become ever so slightly creamier as it warms in the glass but still shows its salinity. It certainly won’t be for everyone – I brought it to a BYO tasting last year and many people, myself included, found it difficult to get to grips with. A second bottle, enjoyed at home with sashimi, was sublime however.

With thanks to Cuatrogatos Wine Club, these bottles were ‘suitcase wines’ from my most recent trip to Jerez. It’s fitting therefore that Alex recently suggested to me that those mid-air pictures of clouds that people Instagram from airplanes often remind him of flor. I must admit that I hadn’t made that association before, but while looking back at my most recent snap from somewhere over the Irish Sea I’m inclined to agree.

A fascination to be fostered at 37,000 feet.



Julian Jeffs – Sherry
Christopher Fielden and Javier Hidalgo – Manzanilla
Peter Liem and Jesús Barquín – Sherry, Manzanilla and Montilla
W.V. Cures – Investigations of the Flor Sherry Process.
B. Esteve-Zarzoso et al. – Yeast Population Dynamics during the Fermentation and Biological Aging of Sherry Wines. International Journal of Food Microbiology 167 (2013)
H. Alexandre – Flor yeasts of Saccharaomyces cervisiae – Their ecology, genetics and metabolism. Applied and Environmental Microbiology, May 2001