Mixology Planet Tour 2012

In Part II, I summarized what our class learned of the process Sherry goes through prior to aging from Katie Stipe and Phil Ward. In Part III, I will attempt to summarize what they taught us about the Sherry aging process.

Although in the past various vessels were used for transportation and aging, today the vast majority of Sherry aging takes place in bodega butts (barrels). These are composed of American oak with a 600L capacity and have been wine seasoned in order to limit any wood effect on the wine’s flavor.

Sherry butt construction (from www.sherry.org)

As mentioned earlier, usually “two fists” of airspace is left in the barrel to allow the flor to develop. These barrels absorb water from the Sherry at a rate of up to 3-5%/year, depending on the bodega’s humidity. The result is a concentrating of all the other components in the wine. Minimum aging according to the regulations of the DOM is 3 years.

The first 6-12 months of aging in barrel is referred to as sobretablas stage. (The fortified olorosos, as designated in the first classification, may skip this step and be introduced immediately into the next stage of aging or stored in what is called añadas. Over the course of the year, the young olorosos in añadas will be gradually introduced into the next stage of aging in the process called trasiego.)

This stage is most important for the wines initially designated finos and fortified to 15%. How they develop during sobretablas determines the wine style that will emerge at the final stage of production. The first classification was completed after only a couple weeks. The second takes place at the end of sobretablas and the tasters have a couple more options for classification available.

Second classification of fino Sherry. (from www.sherry.org)

If the flor film on the wine in the butt has flourished, the wine retains or enhances its finesse and paleness, and has begun to exhibit the characteristics of biological aging under flor, it is again classified as fino and marked as such (/).

Some wines, while deemed suitable to continue biological aging as fino, are determined to have very special characteristics which vary according to house style. They are classified and marked as palo cortado (/). Although these wines may spend some more time in sobretablas under flor, they will eventually be further fortified to 17% ABV. The flor will die and the palo cortado will begin its second aging process, oxidative aging.

from www.sherry.org

If for any reason the flor film has begun to fade or has disappeared completely at the end of sobretablas, the wine initially considered suitable for biological aging is re-classified. It is marked as oloroso(0), fortified to 17%, and also begins its second, oxidative aging process.

Finally, some wines are deemed unworthy of becoming Sherry in the second classification. They may be too high in acidity or may exhibit other unsuitable characteristics. These are marked (#) and are removed from the Sherry production process.

from www.sherry.org

With the second classification complete, Sherry moves into the “Criaderas y Solera” aging system. As mentioned in Part I, this system arose after the Vintner’s Guild was abolished in the late 18th century to create a consistent aged wine from various vintages. It is now the traditional aging process for Sherry. It is also vital for the fino and manzanilla Sherries that must undergo biological aging for at least 3 years. This will become apparent after the Criaderas and Solera process is understood.

Criaderas and Solera system (from www.sherry.org)

The Criaderas and Solera system is a fractional blending system where younger wines are blended into older wines. The oldest, finished Sherry is contained in the first tier of butts resting on the floor called the “Solera”. Solera is derived from the word “suelo” (floor). On top of the Solera are usually another 2-8 tiers of butts, depending on the bodega, age and type of Sherry. These are called “Criaderas” (nurseries). The 1st Criadera is closest to the Solera, the 2nd Criadera is above the 1st Criadera, and so on.

Solera and 3 Criaderas (from www.sherry.org)

When finished Sherry in the Solera butts is removed for bottling in the process called “saca” (taking out), it creates space in each butt for replenishing with Sherry from the 1st Criadera butts. In turn, the 1st Criadera is replenished from the 2nd Criadera, and so on until the final Criadera on top is replenished from Sherry having just finished the Sobretablas stage. The process of replenishing is called “rocio” (sprinkling). Between the rocio and saca process, Sherry from each of the butts of a particular Criadera are blended together for consistency. The entire process is called “correr escalas” (running the scales).

"Rociando", just one part of "correr escalas" (from www.sherry.org)

Running the scales is very specialized work done using traditional methods. The workers must be careful during the saca and rocio not to overly disturb the flor on top of the Sherry or the “cabezuelas” (fine lees) at the bottom of the barrel.

Conversely, running the scales will cause additional oxygen to become dissolved into the Sherry during the transfer process. This is advantageous. The small amount of extra oxygen helps the flor in the oldest fino and manzanilla Sherry’s to regain its vitality. It will also slightly accelerate the process in the Sherry undergoing oxidative aging, .

In addition to oxygen and alcohol, flor requires other micronutrients found in the fino and manzanilla Sherry.  Without being “refreshed” by younger Sherry from the Criaderas, the flor in the Solera butts would eventually consume all the micronutrients, begin to fade, and allow oxidation of the wine. This is why biological aging for Sherry would not be possible without the Criaderas and Solera system.

The average age period of the Sherry in the Solera is determined by dividing the total volume of Sherry in the Criaderas and Solera system by  the amount that is removed annually for bottling. Since the minimum age for all Sherries is 3 years, a maximum of 1/3 of the total volume of Sherry in the system can be bottled annually. For example, if the age statement on the bottle is 12 years, there must have been at least 12 L in the Criaderas and Solera for every 1 L removed from the Solera for bottling.

Part IV will summerize the final classifications of Sherry and briefly discuss Sherry in cocktails.

In Part I, I touched on some of what we learned from Katie Stipe and Phil Ward about the terroir in the Sherry Triangle and some interesting facts about the history of Sherry. This post will summarize some of the unique aspects of Sherry production prior to aging.

After recovering from the phylloxera epidemic, Sherry has been primarily produced using the white Palomino grape (90% of all sherry grapes) along with Moscatel and Pedro Ximenez grapes. The Moscatel and PX grapes are used for sweeter styles of Sherry and are laid out on grass matts in the sun for 12 days after picking to concentrate the sugars. These two grapes also go through a slightly different fermentation and aging process to that described below.

Vara y pulgar (from www.sherry.org)

The pruning of the vines uses an interesting technique called “vara y pulgar” or “stick and thumb”. They train the vine to have two branches. Each year one is trimmed down to a couple buds (the thumb) and the other is allowed to grow out (the stick). This focuses all the energy of the vine into one branch each year and extends the productive life of the vine (30 to 35 years). Harvest, during which 75% of the grapes are still hand-picked due to the low vine height, is usually in early September and the exact timing is driven by the sugar level present in the grape.

Initial crush of the grapes (from www.sherry.org)

The grapes are crushed and optionally de-stemmed prior to extraction. There are two extraction presses, or “yemas”. The first yema utilizes light pressure and the composition of this grape must is more suitable for younger styles of sherry such as finos and manzinillas.

The second yema doubles the pressure, extracting more must from the solids and making it more suitable for the oxidative aging of the older styles of sherry. Any must resulting from pressing the remaining paste at higher pressure cannot be used for Sherry production.

Prior to fermentation, the must is clarified. Fermentation is done predominately in stainless steel. The first fermentation is usually instigated in a process known as “pies de cuba” wherein already actively fermenting must is added back into the new must. 95% of this “tumultuous” fermentation is completed in the first 7-10 days. The second, slower fermentation takes place over the following weeks as the autumn temperatures drop and the remaining sugars are converted to alcohol. The fermented must self-clarifies during this time as the lees (dead yeast) settles to the bottom.

Flor film over sherry in barrrel. From www.sherry.org

As the lees settle to the bottom and are then removed, an indigenous yeast called “flor” begins to form on top of the fermented must. This yeast has very special characteristics. It has evolved to live off of alcohol and oxygen as well as unfermented sugars and other components in the wine. In turn, flor releases new components, most importantly acetaldehydes.

Since this yeast requires oxygen, fermentation is open and aging is done with the barrels or “butts” open. For ideal sherry aging, the butts are filled to no more than 5/6ths of their volume (“two fists of air”) to allow the flor sufficient oxygen. This also is why the bodegas were designed to hold high volumes of humid, circulating air. The name “flor” means flower, and this references the fact that the ideal temperature and humidity for flor growth occurs in the autumn and spring. Finally, flor only can live within a specific range of alcohol content. This will affect the style of wine that results when the producer fortifies it prior to aging.

Prior to fortification and aging, the wine is classified. To this point, the condition of the harvest, the location of the vineyard and its microclimate, whether the wine was first or second yema, and the process of fermentation have all contributed to creating a unique wine. Tasters now determine if the wine displays more finesse and paleness (usually 1st yema) or if they have a heavier, or “gordura” structure (usually 2nd yema) appropriate for oxidative aging. They accomplish this both through lab analysis and actual tasting. The first are categorized as finos, marked with a “/” and the second as oloroso, marked with a “O”.

The wine  has reached 11-12.5% ABV due to fermentation. Hundreds of years ago fortification of Sherry was used to stabilize the wine for extended travel. However, after the Vintner’s Guild was abolished, the aim of fortification developed to become deterministic of the style of fortified wine produced through the two different Sherry aging processes. The wine the producer has determined to develop into either fino (/) or manzanillas will have neutral, unaged grape brandy spirit added to achieve 15.5% ABV. The wine destined to become oloroso (O) will be fortified to at least 17% ABV.

This decision has huge implications for the style of Sherry that will emerge from aging and recognizing this is important to understanding the complexity and diversity of Sherry. The fino or manzanillas will now undergo biological aging. The 15.5% ABV is such that flor will continue to develop but other microorganisms cannot. The composition of the wine will change biologically during the aging process but the flor film over the top will prevent changes due to oxidation. As Phil said, “This is the truth, nothing lies in here” … there is very little barrel effect or oxidation to change the inherent nature of the Sherry.

In contrast, at over 17% ABV even the alcohol loving flor cannot survive and biological changes cannot occur. Only oxidative aging is possible. The flor film will fade away and a slow oxidation will occur, hence the darker colors that result in these Sherries.

Part III will touch on the Sherry aging process, especially the Criadera/Solera system.

Last week we were treated to a great presentation on Sherry from Last Call Consulting partners Katie Stipe and Phil Ward, also owner/operator of Mayahuel, NYC. It was an extensive 4 1/2 hour session covering the history and production of Sherry, a tasting of eight different Sherries, and a discussion about the use of sherry in cocktails. We ended with a chance to hand craft our own cocktails using Sherry. I will attempt to summarize some of what we learned.

The “Sherry Triangle” where the grapes are grown is roughly defined by Sanlúcar de Barrameda, Jerez de la Frontera, and El Puerto de Santa María in south-east Spain. Being one of the southern-most wine producing regions in Europe, the prevailing climate in the area of Jerez is warm and consistent. Summers are dry and there are 300 days of sunshine a year. With the Atlantic to the west, there is sufficient humidity, especially at night when a blanket of fog may rest over the vineyards. These westerly Atlantic winds, called “Poniente”, are balanced by south-easterly hot, dry winds from Africa, called Levante.

from www.sherry.org

Most rain comes in the autumn and winter, a surprisingly high 620 L/year. This is quite sufficient despite the dry summers because of the soil in many of the vineyards. Called “alberiza” it is rich in the limestone/calcium carbonate (up to 40%) left by marine fossils, clay, and silica. This soil sucks up water like a sponge and crusts over in the dry summer, retaining the water below and reflecting a stunning white color. Root systems grow very well in this soil, with 12 m long roots found up to 6 m deep. The soil tops rolling hills, with a soft 10-15% gradient.

Sherry has a long history, with viticulture in the area of production near Jerez, Spain dating back over 3000 years. This production even survived Moorish rule as wine could be used for medicinal purposes and the grapes could be converted to products like raisins. The name Sherry even derives from the Moorish name for the city of Jerez, Sherish.

It has been known as a “traveling wine” from the beginning, having been traded throughout the Mediterranean. Once it became fortified, it was able to travel even further distances. In his famous voyage, Magellan made it the first wine to circumnavigate the globe, spending more on Sherry provisioning than on arms.

The more “recent” history of Sherry dates to the late 1700’s. Consumer tastes in Europe had trended to stronger flavored, aged styles of wine. Producers wanted to meet consumer demand while growers in the Vintners Guild preferred to sell younger wines in order to get their investment back much faster.

In the decades following 1775, producers and consumers won out and the Vintners Guild was abolished. This was the important in terms of Sherry production because fortification was now going to be used for more for stylistic purposes in the aged wines, rather than solely for preservation of younger wines. Also, the Solera/Criadera aging process of blending older Sherries with newer vintages evolved because of the prolonged storage of different vintages and the need for a consistent product for the consumer.

Interior of a Sherry Bodega.

This change in emphasis to aging also resulted in the building of the great Bodegas, with the architecture optimized to create ideal aging conditions while reflecting the prevailing neo-classical style of the day.

Sherry aging requires regulated temperature and humidity, which as we learned is not easy to find in the Sherry triangle if you don’t have modern climate control. Clever design was required to utilize the strengths of the climate while minimizing its difficult aspects.

Unusually high ceilings allow heat to rise. It is then naturally vented through the arch design, out of openings placed high on the east and west facing walls. The height also gives the bodega interior a large volume of oxygen, necessary for the growth of the yeast, or “flor” (which is critical in the Sherry aging process). The high windows, covered with blinds during the day, filter the air and create a consistent and diffuse light, irrespective of the sun’s position.

Exterior of Osborne Sherry Bodega

The rectangular buildings are oriented to allow flor friendly humidity in from the Poniente winds. The orientation also blocks the hot, dry Levante winds and minimizes exposure of the walls to the most intense sunlight. Porous walls let in the humidity but because they are thick and thermally inert, they block out the summer heat. In the summer, vegetation on the south walls protects from direct sunlight. In the winter, with the leaves gone, the sunlight is able to warm the whitewashed walls, which in turn transfer the heat into the bodega during the cool nights. Finally, the floors are covered with porous albero earth. When saturated with water, it lowers the Bodega temperature and keeps it cool by slowly releasing water into the air.

Vegetation protecting exterior wall of bodega from direct sun. (from www.sherry.org)

Part II will touch on the production of Sherry prior to aging.