Otto Nieminen wrote:I understand that what becomes Palo Cortado starts out life as destined for Fino or Amontillado but loses its Flor. What are the reasons that can cause the wine to lose the Flor and oxidize?
Not exactly, Otto. Theoretically, a palo cortado has never been under flor. When a must is sufficiently fine and light (usually coming from specific vineyard sites, such as Balbaina or Miraflores, that are closer to the sea, planted to the 'palomino fino' clone of the palomino grape and have a soil that's particularly rich in 'albariza' limestone), it's fermented in vats (formerly old oak, now mostly stainless) that are far from full, which enables the Saccharomyces yeasts to form the 'flor' or veil on the surface that will protect the wine from oxidation. Theses wines are destined to become finos (or, in the coastal town of Sanlúcar de Barrameda, manzanillas). The flor eventually dies out. In some vats or barrels it dies faster, leaving the wine the continue its aging in oxidative fashion: this is amontillado, not palo cortado.
Palo cortado comes from the other side of the dry sherry family: the side that's aged under no flor from the start. When a wine shows 'gordura' (literally, 'fatness'), it's destined to become the smoothest, roundest, fullest type of sherry: oloroso. But in old, less scientific times, some of those sherries chosen to become olorosos steadfastly "refused" to develop the required roundness and showed a proclivity to be lighter, finer, more pungent: they seemed to strive to become an amontillado, not an oloroso. This was a palo cortado ('cut stick', from the chalk sign that was used for it on the barrels). In the recent past, this 'haphazard', almost legendary way of obtaining a palo cortado has probably been replaced with a surer method: simply, a fine, light must from Balbaina or similar sites is selected to be fermented without any flor, so that from the start it's pre-determined to become a palo cortado.
In practice, some wines that have seen flor can be labeled 'palo cortado', and possibly some wines that have never seen it wind up as 'amontillado'. Usually Jerez wines are finally ranked, at release, through tastings, and I've seen reports that the same soleras can be labelled differently at different times in their lives because their taste and aromatic profiles slowly mutate. Julian Jeffs wrote about Williams & Humbert wines from 1929 that in 1957 were being bottled as oloroso and in 1987 as palo cortado; or wines from 1937 that were initially amontillado but in 1987 had become palo cortado.
