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The first stage of making sherry is to create the Base Wine. For sherry, this first process is similar to how wines are made around the world: grapes are harvested at just the right time to capture the desired balance of flavor and sugar levels, then they are crushed and fermented to create the Base Wine. For dry sherries, the Palomino grape yields a base wine of 11-12% alcohol by volume. For sweeter sherries, which are made from Moscatel and Pedro Ximenez grapes, the fermentation is shorter so as to leave some of the sugar remaining in the Base Wine.
From this stage onward, however, the crafting of sherry is a quite unique process and very different from ordinary wines.
The sherry base wine is now fortified with additional alcohol up to 15%-17% ABV, and placed into barrels in the Bodega for aging, using the Solera system of fractional blending.
Think of a Bodega simply as a winery for sherry. From crushing of the grapes to fermentation to aging, the Bodega is the birthplace of a sherry. Some Bodegas are very small, with only a few dozen barrels of production, while others are quite large and cathedral-like, such as this Lustau Bodega below, where the Lustau “Jarana” Fino sherry is made:
All sherries are aged in Bodegas. In many cases these Bodegas are many decades old, and they incorporate centuries of architectural wisdom on how to manage air flow, temperature, humidity, and other key variables in the sherry aging process.
The Solera System
Unlike other ordinary wines, which can change quite dramatically from one vintage to the next, the Solera system ensures a more consistent product from year to year. It requires that only a portion of each year’s production be bottled, with a sizeable portion saved to be blended together with the next year’s production. The principle is somewhat similar to that of an artisan breadmaker, where a portion of the dough is saved as a starter for the next batch; except with sherry it’s a bit more complex.
Let’s use the picture above as an example. The barrels are typically stacked three rows high. When bottling, wine is taken from the bottom row only (refererred to as the “solera” wine, implying it’s finished to the solera standard.) The row above that is referred to as the “1st Criadera”, implying it’s about 1 year or 1 stage away from being the solera’s finished wine. And the top row then is the 2nd Criadera, or 2 years or 2 stages away from finished. In every case, the Fractional Blending requirement dictates that only a portion of the wine on the “solera” level can be taken to bottle. The rest remains in the barrel, and is replenished with wine taken from the level above it. Then, those barrels are topped off with wine from the top row. And finally, the top row is then refilled with the new year’s production. In this way, a portion of the wine remains every year to be blend in with the next year’s, leading to better quality, unique wine character, and consistency from year to year.
This is a complex system that requires precise inventory management and attention to detail, and it is more costly than simply bottling everything all at once each year. But, the Solera system is a key part of what makes sherry so unique, and remarkably consistent from year to year. By law, all Bodegas must follow this process.
What happens inside those barrels adds even more complexity, and creates the various styles of sherry. There are two fundamentally different ways that sherries can be aged: Biological, or Oxidative. Each produces different types of sherry.
With biological aging, the fortified base wine is barreled and left to its own devices. Naturally occurring, wild yeast strains settle onto the surface of the wine and begin to grow, creating a layer of flor (literally, “flower” of yeast) on top of the wine as it ages.
Essentially, each barrel becomes its own dynamic, living biosphere! As the yeast propagates, it not only creates special flavors in the wine, it also performs two other important functions. First, the yeast is eating up the remaining sugar in the wine. If allowed to complete its mission, the yeast will eat virtually all the sugar and result in wine with nearly zero net carbs! The second important function of the layer of flor is to protect the wine from oxygen, which preserves and enhances the natural flavors of the grape.
Following the rules of sherry-making, only Palomino grapes can be aged under flor. The resulting wines are only Manzanilla if aged in the town of Sanlucar de Barrameda, or Fino if it is aged anywhere else in the Sherry Triangle. (We’ll discuss the characteristics of these two and all the other various styles of sherry later in the course.)
However, after the biological aging is complete the winemaker may choose to continue with further aging of the wine in oxidative conditions, which means in contact with the air, or oxygen. The resulting sherry will be Amontillado.
Or, in some cases Mother Nature intervenes and the flor may die off earlier than expected in a particular barrel; these barrels are also moved into oxidative aging. At the winemaker’s discretion, some may become Amontillado, or those barrels with special character are set aside to eventually become Palo Cortado sherry.
While the biological-aging-only sherries of Fino and Manzanilla are crisp, bright, light, and refreshing, those sherries that undergo oxidative aging become richer, fuller bodied, with more structure.
Oloroso is a major type of sherry which is also made from the Palomino grape like those above, except the base wine goes directly and only into oxidative aging. Oloroso sherry is the richest and typically the oldest-aged sherry among the dry sherry styles.
The two main sweeter styles of sherry also undergo oxidative-only aging, but they come from different grapes. Moscatel sherry is made from Moscatel grapes, and Pedro Ximenez is made from the Pedro Ximenez grape. Both are harvested very late, so as the let the grapes accumulate extra sugar, then sun-dried into raisin-like fruit with exceptional flavor concentrations. Only then do they undergo fermentation, fortification, and aging.