Chapter 8

Maturation of Wine

Wine Maturation Vessels

Wines are aged in many different types of vessels, from stainless-steel tanks, to oak barrels, to concrete, or plastic tanks (Chapter 22). The decision to which vessel to use depends on the style of the wine, budget, or materials at hand. The choice is evident in the finished wine. Stainless steel tanks are widely used for white wines, and sometimes reds, where a fresh, crisp, and fruit forward aroma and flavor is desired. Oak barrels vary depending on where the barrels are from, how they are made, and how old they are. American oak and French oak are the two most common types seen in winemaking.

Stainless-Steel Tanks

Aging in stainless-steel tanks is neutral, it adds nothing more to wine than a container to hold it as it evolves and matures before bottling (Section 22.3). Winemakers who steel age believe it allows the grape varietal to speak without any influence of wood. They maintain the terroir (vineyard's elevation, type of soil, position of a hill or slope, weather nuances, orientation to the sun) is more clearly expressed in steel aging, resulting in complex yet not overly complicated wines.

Oak Barrels

As opposed to stainless-steel tanks, wine maturation in oak barrels affect the wine's taste and mouth feel, adding aromas, tannins and textures (Chapter 21). Maturation in oak barrels has three effects not available when stainless steel alone is used: (1) extractives are furnished from the oak to the wine; (2) porous nature of an oak barrel causes evaporation allowing wine to concentrate its flavor and aroma compounds; and (3) because oak barrels are porous, exposing the inside to outside air, wine is allowed to slowly breathe or oxygenate acting as a softening agent upon the wine's tannins.

Medium and Full-Bodied Premium Wines

Medium and full-bodied premium wines are commonly matured in oak barrels. Bordeaux varietals - Cabernet Sauvignon, Merlot, and Malbec - are just a few red grape varieties suitable for barrel aging. The white wine that is most often seen aged in oak is Chardonnay. Chardonnay is considered a non-aromatic grape, as its aromas are usually basic orchard fruit, like apple and pear, and perhaps some citrus notes. During maturation in barrels, there is a more intimate contact with the wood surface than in larger stainless-steel tanks.

Concrete Tanks

Oak barrels have long reigned supreme across the wine world as the primary maturation medium. An oak barrel imparts flavors compounds including aromas of vanilla, clove, smoke, and coconut to the wine and allows the slow ingress of oxygen - a process which makes wine taste smoother and less astringent.While stainless steel has long been a go-to neutral vessel what the material doesn't offer is that aspect of breathing the air, allowing air in and out of the container and having it interact with the wine over time. An alternative material to oak and stainless steel is concrete, often egg-shaped vessels, for the maceration, fermentation, and maturation of wine (Section 22.3).

Plastic Tanks

For decades the wine industry has used stainless steel tanks of all sizes, large and small wood tanks made of trees ranging from redwood to oak to chestnut, and concrete tanks. Historically, barrels have been unique in their natural ability to meter oxygen in a controlled way that allows the gradual changes necessary for the development of the flavors and aromas desired in an aged wine.

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