One of the most southerly vineyard areas of Europe, Jerez climate is Mediterranean with strong Maritime influences and is particularly warm due to low-lying latitude. Very hot and dry summers create some arid conditions which are only diminished by the humidity levels originated from the Atlantic Ocean that also has a cooling temperature effect.
Average annual temperature is 17.3ºC with very mild winters, and extreme summers with temperatures frequently above 40ºC. There is an average of 300 days of sunshine, accounting for between 3,000 and 3,200 hours of effective sunlight, which is ideal for long hanging times and for drying grapes in open air to concentrate sugars. Levels of rainfall are on average 620 l/m2 per year, usually falling in autumn and winter.
Very important to mention the two prevailing winds known as the cool and humid Poniente (from the west with 90% humidity) and the hot and dry Levante (from the south-east with 30% humidity).
There are marked climatic differences between the different sub-zones, districts and pagos which make up the sherry-growing area known as the Marco de Jerez.
The special micro-climate of Sanlúcar de Barrameda, a town built on two terraces at different levels: one at sea level (the Barrio Bajo or low quarter) and the other a few meters higher (the Barrio Alto or high quarter) for instance accounts for a DO of its own, the Manzanilla. The nuances are imparted by 3 main features:
- River Guadalquivir; - The Atlantic Ocean into which the river flows; - The Marisma, an extensive stretch of wetland on the former river delta which is completely flat.
These combined generate milder temperatures and higher levels of relative humidity than those prevailing in the rest of the Jerez Region: a humidity which is carried in on by the sea-breeze, a westerly wind that is detained when it strikes the natural barrier formed by the Barrio Alto, depositing its moist air upon the urban centre of the town.
All these circumstances foster the growth of the flor, the characteristic film of yeast that is peculiar to Sanlúcar and endows those wines biologically aged in its bodegas with special organoleptic characteristics.
Best vineyard areas are covered by a limestone soil known as albariza, which is rich in calcium carbonate, clay and silica from the diatomite and radiolite shells present in the sea that once covered the region.
This soil has a high porosity being able to absorb the intense rainfall in the winter and store it effectively to avoid the roots from drying during the hot dry summers.
Albariza soil is easy to work and, being very moisture retentive, facilitates an excellent distribution of the root system. Roots up to twelve meters in length have been found at depths of up to six meters in albariza soil. These soils are responsible for producing the most delicate wines for the finest Finos and Manzanillas.
At a lesser extent other types of soil can be found in the region and used for the production of Sherry. These are barros (clays) mainly found in the valleys, producing fuller, coarser wines with slightly higher yields, and arenas (sands) found in coastal areas, with doubled yield capacity than albariza, produces a lower quality wine.
GRAPE VARIETIES AND VITICULTURE
The Regulations of the Consejo Regulador indicate 3 white-grape varieties as being suitable for the production of Sherry:
Accounting for almost 95% of vineyard planting nowadays, Palomino is the trademark grape of Jerez, especially the sub-variety Palomino Fino - the most commonly used throughout the region, totally adapted to the albariza soil, the local climate and the techniques developed by vine growers.
It is considered as a key element in the production of Generosos sherry wines, due to the referred adaptability and the excellent quality of the grapes and its responsiveness in the vineyard. Yields are in the order of 80 hectolitres per hectare, registering around 11 degrees Baumé and low acidity.
Of much lesser importance is the sub-variety "Palomino de Jerez" which generally produces smaller yields with slightly higher levels of sugar and acidity.
This grape is known around the World as one of the dullest varieties, but in this south west Spanish climate, planted in the albariza soil and aged in a Solera system it is capable of producing wines of matchless complexity and pungency.
It is mainly used solo, to produce dried fortified sherry wines know as Generosos (Fino, Manzanilla, Palo Cortado, Amontillado and Oloroso), but can also be blended with the following two varieties.
Also very traditional, its greater sugar content (12.8º Baumé) and higher levels of acidity produce sweet wines of great quality. These grapes are generally submitted to a "sunning" process before they are vinificaton, with the aim of intensively concentrating the sugar content of the grape. Its fine leafage facilitates the process.
A variety used in the Jerez Region for the production of wines by the same name, gives special sweet wines, usually coming from "sunned" grapes of the highest quality, showing intense grapy perfume. The vines of this variety are best suited to vineyards located close to the sea.
PX and Muscat are used by themselves to produce the Naturally Sweet Wines category, which take the names of the grapes as nomenclature, or are blended with Generosos, in the form of concentrated must, to obtain the Generosos Liquer Wines (Pale Cream, Medium and Cream Sherries).
These grape varieties are planted in order to reach an ideal height ranging between 60cm to 80 cm from the ground. Vines are trained on wires and pruned in the “Vara e Pulgar” method, which is very similar to the Guyot method, consisting of two canes growing from the permanent wood, the vara will have seven or eight buds that will be responsible for the current year’s crop, and the pulgar, a short shoot with only one bud which will produce the following year’s bud.
VINIFICATION AND FORTIFICATION
Generoso Wines (Fino, Manzanilla, Palo Cortado, Amontillado and Oloroso)
Generoso wines are defined by the Regulations of the Consejo Regulador as dry wines (with a maximum residual sugar quantity of 5 grams per litre) produced from the total fermentation of must, usually produced from Palomino grapes, at the end of which process a film of yeast known as flor appears upon the surface of the base wine.
After the crushing process there is a key activity to define the wine style. The extraction system where pressure is applied in order to obtain more must. There will be two levels of pressure resulting in different must compositions:
- "primera yema" must (approximately 65% of the total volume), obtained with pressures of up to 2 kg/cm2 . This delicate free run juice will be particularly suited for the production of wines intended for biological ageing; - "segunda yema" must (approximately 23%), obtained with a pressure of up to 4 kg/cm2 - "mosto prensa" produced by applying a pressure of over 6 kg/cm2.
Whilst the particular analytical characteristics of primera yema must make it suitable for biological ageing, segunda yema must, much more structured from the higher solids influence is used to produce wines better suited to oxidative ageing.
The Regulations of the Denomination of Origin regarding extraction methods state that only those musts obtained from a maximum yield of 70 litres for each 100kg of grape may be used to produce Sherry Wine. The rest of the must, obtained by higher levels of pressure may be used to produce other, non-classified, wines, for the production of wine for distillation or to obtain other sub-products.
In the case of Generosos, around the end of October the new wine of the year - known as "base wine" - is ready for racking and it will be a completely dry white wine, pale, delicate, slightly fruity and low in acidity which will constitute the base for the later production of Sherry Wines.
At this stage wines will be tasted by specialists for a first definition of style and classification. The most elegant, pale and delicate wines, generally from free run juice, will be marked to be aged as Finos or Manzanillas and undergo biological ageing; the more structured batches will be marked to be Olorosos and will be aged in oxidative fashion.
The process of fortification will then follow, stabilizing wines and giving them special oenological characteristics, by mixing wine and alcohol until the correct alcoholic strength is acquired. The style of fortification will be applied according to the former classification to attain the desired ageing process, defining how the wine wil develop further in cask:
- Wines classified to age as finos and manzanillas are fortified until they reach a total alcoholic content of 15.5 per cent by volume. This level will allow the yeast cells to form the flor, but at the same time intolerable for other micro-organisms to develop in the wine. In short, we are selecting the type of biological activity which we wish the wine to undergo, which is that developed by the yeast responsible for the film of flor. The flor will then cover the surface of the wine and thus prevent its oxidation, facilitating a whole series of changes to its composition: a process known as Biological Ageing.
- Those wines classified to undergo ageing as olorosos are fortified in such a way as to reach an alcoholic content of at least 17%, therefore stopping all biological activity by killing every yeast strain. This will allow the wine to maintain direct contact with air, this way experiencing a slow, unalterable process of oxidation, accompanied by a gradual darkening in color. This is Oxidative Ageing.
The most distinctive characteristic of wines made in Jerez, is the natural formation of a film-like culture of yeasts, covering the whole surface of the wine, known as “Flor” and responsible for the biological ageing characteristic of Finos and Manzanillas.
This special strain of indigenous yeasts is naturally more resistant to alcohol, and will stay on top of the base wine, protecting it from oxidation and at the same time imparting it unique organoleptic characteristics.
As levels of alcohol in the new wine reach their limit, these unusual yeasts form upon the free surface of the wine inside the butt, surviving with the help of oxygen from the air, correct levels of humidity and temperature and by metabolising part of the alcohol and other components contained in the wine.
Naturally Sweet Wines
The vinification of Pedro Ximénez and Muscat, destined to the production of Naturally Sweet Wines is distinct from the Generosos.
PX wines are produced exclusively from over-ripe grapes, picked once they have attained a high concentration of sugar on the vine, in excess of 16 degrees Baumé (around 300 grams of sugar per litre of must). Once harvested the grapes are spread out on paseras, special sites set aside for drying out the fruit in the sun, a process known as soleo, or sunning. The grapes lose a great deal of water during the sunning process, also known as pasificación, therefore concentrating their sugar content (450-500 grams per litre of must). In parallel to this increase in sugar, other changes take place in the chemical, physical and sensory features of the dried, "raisined" grape: heightened colour, density, viscosity, stickiness and the emergence of typical aromas and flavors.
After several days, normally 7 to 15 depending on weather conditions (temperature and relative humidity), once the grapes are judged to have reached the optimal condition, they are collected and transported to the wine press for the next stage in the process, the extraction of must. This process is harder than normal due to the heavy dehydration of the grapes
So the rule is to use vertical presses, where grapes are piled up in layers divided by their drying esparto grass mats. This will facilitate the extraction of this extremely dense, viscous must
Their high concentration of sugar affects spontaneous fermentation, which gets under way slowly. In order to stabilize fermentative microbiological activity in the musts, wine spirit is added to levels not far short of 10 degrees of alcohol. Thus stabilized the wine is left to settle during the autumn and winter months, after which the new wine is racked to remove any lees and further fortified up to 15 to 17 degrees of alcohol. The wine is then left to age in American oak casks, using the traditional añada and solera systems.
Moscatel wines are made exclusively from grapes of the Moscatel de Alejandría variety, which are harvested when very ripe. Moscatel grapes can also be sunned to obtain moscateles pasas as for PX, only this grapes will be less shriveled due do its bigger size. This process will take place on paseras of sand, as Moscatel grapes are found mainly in sandy soils near the sea.
Generoso Wines (Fino, Manzanilla, Palo Cortado, Amontillado and Oloroso)
After fortification, the wines will be transferred from the tanks in to wood butts to initiate the maturation process.
This process is sub-divided into two stages; the Sobretabla is a first ageing stage carried out in 500 litter wood butts of about 6 to 8 months, preceding the final entrance into the ageing system. This intermediate stage is especially important to those wines initially classified as finos, as after this period all wines will be re tasted for a second classification, and only then will they be marked as definitely being a Fino or a Manzanilla, or instead if they will continue their maturation process as an Oloroso.
The olorosos, which in the first classification were considered by the tasters to possess a defined structure and suitable organoleptic characteristics, once fortified then take their place in the ageing systems.
After the exhaustive selection process of the second classification, the wines are now ready to feed the criaderas of the different final ageing systems know as Crianza.
The two types of crianza available are as mentioned the Biological Ageing process suited for Finos during which the wine develops in a more dynamic way due to all the interactions with the living layer of yeasts.
Finally Oxidative Ageing, meant for the production of all the styles either than Finos, including Naturally PX and Moscatel Natural Sweet Wines, will take place, accounting for a slow, physic-chemical development influenced by surrounding conditions, known as envejecimiento (maturing). This contact with oxygen will render the wines dark brown and gradually become more concentrated with age due to transpiration of specific elements within the butt.
The Regulations of the Denomination of Origin state that the ageing process of sherry wines must be carried out for at least three years in cask, enabling this way the effective development of each type specific characteristics.
The full range of choices for the tasters at this second classification is as follows:
- Fino or Manzanilla, arise from butts where flor is still present and thriving, actively protecting the enclosed wine from oxidation and subtly transforming its initial characteristics, continuously acquiring finesse. Casks will be marked with a palma symbol to indicate wines will continue ageing below the yeast film of flor. The initial paleness of the wine has been maintained or even enhanced and is exhibiting a fresh sharpness of flavor. Wines will be very pale in colour, very fresh and zesty with autolityc notes and hint of roasted almonds. Palate will be extremely zesty and refreshing making this a perfect partner for fatty delicacies such as Ibérico ham;
- Palo Cortado, will be made from butts in which the flor still remains and the finest must identified by the cellar-master. Although they exhibit distinct finesse and could apparently age under flor, they will be further fortified to a 17% abv in order to initiate the second ageing stage in oxidative fashion, to create this very special category of wine according to criteria specific to each producing firm. Wines will be chestnut to mahogany in color with a complex bouquet that blends the characteristic notes of amontillados and olorosos with more fresh citric notes of grapefruit and lactic notes suggestive of fermented butter. Usually presenting a deep, rounded, ample palate with smooth, delicate aromatic notes appearing in the aftertaste normally long in length;
- Amontillado, once used to describe Sherry from Montilla, it is now a category of its own. True Amontillado happens when the Flor of a basic Fino wine dies naturally, therefore exposing the wine to oxygen. This will happen if the level of fortification rises to 16% abv, as Flor cannot survive in this condition. It can be seen as aged Fino, turning amber in color, and tasting richer and nuttier. Nowadays cheaper versions are more commonly found, achieved artificially by blending and usually sweetening is carried out. This wines are pale topaz to amber in colour, with a subtle ethereal nose smoothed by aromas of hazelnut, aromatic herbs and dark tobacco. Light and smooth palate with well-balanced acidity; both complex and evocative, giving way to a dry finish and lingering after-taste with a hint of nuts and wood;
- Oloroso wines can also show up at this second classification, if wines previously thought to be able to produce Finos are presenting signs that flor is not developing correctly, is losing vigour or even dying off. Therefore there will be no other option than further fortifying to 17% abv preparing them for oxidative ageing to reach an Oloroso sherry. Darker with rising age the color ranges from rich amber to deep mahogany. Warm, rounded aromas which are both complex and powerful. Aromas are dominated by walnuts, with toasted, vegetable and balsamic notes reminiscent of noble wood, golden tobacco and autumn leaves. There are noticeable spicy, animal tones suggestive of truffles and leather. Palate shows pronounced intensity and wines are very well structured with a powerful, well-rounded and smooth full body. Best wines have prolonged aftertaste showing aromas of noble wood in an elegant dry finish.
Although in the case of oxidative ageing it is possible to age the wines in single casks statically without blending, traditionally wine ageing in Jerez is carried out in a dynamic system known as Solera. This is in fact the only way possible for biological ageing.
This is a method of fractional blending through which the wine in the butts is continuously replenished in order to maintain the Flor alive for Finos by replenishing its nutrients and in general to maintain a consistent style of sherry always ready to respond to market demand.
The Solera system is composed by a number of American oak butts of 600 litres that form various groups know as criaderas, stacked on top of each other in different levels, each representing different harvest wines. The final wine will be withdrawn from the group containing the oldest wine, which is known as Solera. This will be replenished by wine from the first criadera that in turn will be replenished by the second criadera, and so on depending on the amount of levels in the system. The whole system is replenished every year with wine from the most recent vintage. This systematic replenishing is called running the scales.
Each year an amount of up to 33% can be withdrawn from the solera in order to sell it, ensuring this way that The Regulations of the Denomination of Origin are respected in terms of the required 3 minimum years of cask ageing.
Most systems will be made out of 3/4 criaderas, but there are very complex soleras that can reach 14 levels.
The following diagram is a part of Jancis Robinson’s Oxford Companion to Wine, and I find it to be the perfect tool to fully grasp the rich variety of styles of this unique and complex wine:
Sources: Clarke, OZ; Rand, Margaret, Grapes & Wines, Pavilliion Books, Ed. 2008 Robinson, Jancis, Oxford Companion to Wine, Oxford University Press, 3rd edition 2006 Consejo Regulador, Sherry DO website, http://www.sherry.org