You're Not Aging, Just Becoming More Mature

This weekend, our class paid a visit to Montalcino, a quaint town about an hour from Siena. The intention of our visit was to understand a little more about the wine making process and of course, to taste two of the wines particular to this town, Brunello di Montalcino (picture to the right) and Rosso di Montalcino. Now, I am no wine tasting expert, but even I could taste the difference between the two wines. The Rosso was more ruby red in color and fruitier in taste, almost sweet. The Brunello was slightly darker, more garnet in color and slightly more bitter, but richer and fuller in taste.

Both wines are made from the same varietal of grape, the Sangiovese Grosso. However, the vinification of each wine constitutes the different tastes. The Brunello is aged longer, required to spend at least two years in oak barrels and two years in the bottle. It cannot be released before the fifth year after the vintage. The Rosso, on the other hand, is ready after one year. Our class visited the La Magia vineyard and took a tour of the cellars, but afterwards I still had little knowledge of what changed during the aging process and why the wooden barrels were so darn important.

The first thing to understand is the difference between the terms “maturation” and “aging.” Maturation is used to describe the changes in wine during bulk storage, where wine can be exposed to air, while aging describes the changes from storage in bottles under anaerobic conditions.

During maturation, wine will change due to differences in temperature, humidity, and even the size and type of storage container. The Brunello that we saw at the La Magia vineyard was stored for three years in barrels made of oak. White oak is used because it is practically water resistant. As the tree ages, the pores in the rings of the tree become clogged with a type of cellular growth called tyloses (seen on the left), which essentially restricts the flow of liquid. This is why other types of wood are less effective in wine maturation, because without the tylose plugs, the wine would drain right out of the barrel.

As for the actual maturation of the wine, oak is important for two reasons. First, the oak holds many volatile and nonvolatile components that can be extracted from the wood while the wine is stored. Some barrels are even prepared through seasoning and toasting beforehand to add certain flavors to the wine. Second, the oak allows oxidation of the wine that will lead to enhancement of color and decreased astringency.

Oak is composed of cellulose, hemicellulose, lignins, and tannins. The barrels are usually toasted before storage of wine because the lignins decompose with heat, creating volatile phenols such as vanillin (vanilla aromas), eugenol (clove-like aromas), and 4-ethyl guaiacol (smokey and spicy aromas). These compounds can all be found in aged wine. Toasting the barrels also leads to compounds like furfural, maltol, and cyclotene, which have characteristic sweet and caramelized aromas. These all come from the breakdown of carbohydrates when the barrel is heated. By seasoning and toasting barrels beforehand, winemakers can control what sort of flavors their wines will take on during the maturation process.

 

(Mike in the La Magia cellars)

 

Breathability of the oak is also important. Here, it’s all about equilibrium. Ethanol and water can escape the barrels as vapor, resulting in some volume loss. The drier the cellar where the wine is stored, the higher the alcohol content of the wine. The more humid the cellar, the higher the water content. Oxygen can then enter through the barrel and replace the lost liquid.

While we have all learned that oxidation can promote spoilage and free radicals, controlled oxidation can positively affect the wine. Controlled oxidation can stabilize the color, moderate the tannin content, and increase the development of intricate aromas. Anthocyanins and tannins take the stage here. We learned in class that anthocyanins contribute to the color of wine. At a low pH level, anthocyanins appear more red in color. As maturation occurs, anthocyanins link with tannins to create polymeric pigments, which aren’t as sensitive to discoloration as pH increases and can produce richer and more intense colors. During this time, tannins can link with other sugars and proteins, softening the astringency and adding a fuller flavor to the wine. All of these combinations rely on oxygen and temperature, which must be closely regulated in order to get the best product.

Oak maturation is only used to produce full-bodied red wines with complex flavors and aromas. Aging this way is not required for lighter and fruitier wines, which are sweeter in taste and cheaper on the market. Putting any type of wine in a barrel won’t make it better, either. A winemaker must assess the quality of the grape before deciding whether a good product can be made through maturation and aging.

For more details, check out some of the webites below. Reading through them definitely gave me a better understanding of the aging and maturation of wine, and ultimately more appreciation for the product.

http://www.ansci.cornell.edu/plants/toxicagents/tannin.html

http://www.food-info.net/uk/colour/anthocyanin.htm

http://www.wineperspective.com/the_acidity_of_wine.htm

http://www.wineanorak.com/tannins.htm

http://www.extension.iastate.edu/wine/oak-aging-red-wine

http://www.fattorialamagia.it/EN/home.html