More Fun than a Barrel of Oak Chips
Winemakers today have lots of choices available to them for fermentation and maturation vessels: stainless steel tanks, wooden barrels of various sizes, ages and types, concrete, and even clay are all options. Their choice of fermentation and aging containers will impact the style and taste of the wine. I generally think of the choice as one of micro-oxidation. Generally oxygen is the enemy to wine but in small and controlled amounts it can create a complex and desired effect. Winemakers will often choose the vessel based on how much oxidation and secondary flavor characteristics they want and when (during fermentation or during aging). Steel allows for almost no oxidation and no additional flavors to be imparted. Whereas wood barrels allow for the most oxidation and flavor.
Types of wood used
If the winemaker decides on wood, they have a lot of choices still to make!
While we often only hear about oak barrels other woods exist for this purpose including Acacia, Mulberry, Redwood, Chestnut.
Oak is generally a favorite because it is easy to bend and shape into barrel staves, is abundant in wine producing countries, has a tight grain that produces water-proof vessels, does not rot when exposed to moisture and has desirable flavors when paired with wine.
Types of oak used
American, French, Hungarian: Oh My! A winemaker has so many choices! Not just what type of vessel, then what type of wood, but now where to source that wood from!? Oy!
Most oak barrels used in wine aging are sourced from forests in America, France or Hungary. They each have their own unique influence on the wine. Here are the highlights:
- American Oak (quercus alba) because of it's wider grain, this wood imparts more flavor and tannins more quickly than other oaks. It's associated with flavors of coconut and vanilla in a wine. Like most things "American" or "New World" is associated with bigger and bolder flavors.
- French Oak (quercus robur & quercus petraea) with its finer grain, French Oak imparts more subtle flavors of hazelnut or smokiness on a wine and is associated with more premium wine making. The 2 oak species robur and petraea are usually mixed in a forest, with robur being more common. It is also more bold imparting more tannins than petraea.
- Hungarian Oak (quercus robur & quercus petraea) Hungarian oak barrels are made from the same oak species as French barrels but at a more approachable cost. In fact, Hungarian forests are populated with a higher concentration of quercus petraea, the more premium and sought after species. For this reason, Hungarian oak is a great value and also a great quality!
Toasting
A lot of the effect of a wines time with oak can come from the raw wood. However by "toasting" the inside of the barrel a winemaker can enhance some of these flavors. Toasting is the process of caramelizing the sugars and in wood by exposing it to a flame. There are different toast levels from light to heavy. A lightly toasted barrel might be exposed to a flame for 25 minutes, whereas heavy toasting may take as long as an hour. If you wanna get really geeky with this, here are how the different compounds in the oak react to different toast levels.
- Vanillin - associated with vanilla flavors in wine is a compound naturally found in raw oak.Increases with medium toast, decreases with very high toast.
- Lactones - associated with flavors of woodiness and coconut in raw oak. Reduces with toasting.
- Eugenol - the main compound in cloves, also found in raw oak, imparts clove and spice flavors on the wine. Increases with toasting.
- Guaiacol - associated with spicy, smoky, charred flavors. Increases with toasting.
- Furfural - This is a family of caramelization compounds associated with sweet, caramel, butterscotch and almond flavors and aromas. Increases with toasting.
But what about chips?
I'm not really covering wood chips, but they are a cheap and fast way that value brands can impart oak characteristics on their wine.
Want to know more about barrels and toasting? Drop me a question in the comments below!