Oak barrels are an important itemthat has various influences on wine.
It may be an exaggeration, but it's no overstatement to say that winemaking cannot be discussed without the existence of oak barrels.
Now, have you ever heardtasting comments related to barrels, such as "this wine is strongly influenced by the barrel," "the barrel use is skillful," or "you don't feel the influence of the barrel"?
Upon hearing such comments,"What is the influence of barrels in the first place?"some of you may be wondering.
Here, I would like to briefly explain the influence that barrels have on wine.
Contact with oxygen
First, the simple influence that oak barrels have on wine is"chemical changes (such as flavor) due to oxygen contact".
Generally speaking, when wine is stored in a225ℓ barrel,20 to 40 mg (per year) of oxygen per literis said to dissolve into the wine.
When oxygen dissolves into wine, polyphenol-related components such as tannins and anthocyanins react,and effects such as more vivid color and softened astringency can be expected.
Oxygen supply in oak barrels has diverse influences on wine, butit may be easier to understand if you think of it as relating to "appearance" and "structure".
While oxidation is an enemy to wine, a very small amount of oxygen supply can enhance the quality of wine.
Influence on flavor
What you should remember among the influences that oak barrels have on wine is the influence on flavor.
Professional tasters comment on "barrel-derived such-and-such...", and if you remember this, you'll be able to understand it somewhat.
First, theoak barrels used to age wine contain various flavor compounds.(The content varies by type. I'll discuss types another time...)
If wine is stored in an oak barrel for a long period, naturally the barrel-derived components are extracted into the wine liquid, so wine that has undergone barrel aging has barrel-derived flavors.
However, the issue is the characteristics of those barrel-derived flavors.
Here's a simple summary.
- Lactone
- Vanillin
- Guaiacol
- Eugenol
- Furfural
- Ellagitannin
- Coumarin
Now, let me tell you what kinds of flavors these are related to.
Lactone
Among oak-derived flavor compounds, one that is considered important islactone.(Also called oak lactone)
Lactone is characterized by coconut and oak aromas, and when heavily extracted into wine, you can feel a strong oak flavor.
It is also said to be related to earthy and grassy aromas in some cases.
By the way, there are French and American oak barrels, but American oak is known for having exceptionally high lactone content, and wines aged in American oak barrels have an intense oak flavor.
Vanillin
When commenting that the barrel is effective, the flavor compound that is probably the key player isvanillin..
As the name suggests, vanillin is the main component of the aroma of "natural vanilla" and is a flavor compound thought to give a vanilla flavor to wine.
Wines with heavy use of new barrels have a sweet aroma, which can be considered to be largely influenced by vanillin. (Is there also an interaction with lactone?)
Guaiacol
It may be an unfamiliar flavor compound, butguaiacol also has a significant influence on wine flavor..
Guaiacol is involved in smoky aromas reminiscent of charcoal.
Depending on the type, it is also said to be involved in spiciness, and if this is too strong, you may feel the wine is somewhat burnt.
However, since smokiness can also occur due to the influence of the yeast Brettanomyces and other factors, this influence may not necessarily all be barrel-derived.
Eugenol
One of the volatile phenols derived from wood,eugenol..
This is also unfamiliar, but it is actually a flavor compound involved in the aroma of "clove."
The fact that red wines that have undergone barrel aging have a clove aroma can be considered to be partly due to this eugenol.
Furfural
Among barrel-derived aromas, what gives a sweet confectionery-like influence isfurfural..
Furfural is involved in flavors like butterscotch and caramel, and while too much extraction can result in a childish taste, in very small amounts it is a notable compound that gives complexity to wine.
It is said to be involved in almond flavor.
Ellagitannin
There are two types of tannins: condensed tannins and hydrolyzable tannins,and the flavor compound that corresponds to the latter is ellagitannin..
It is a compound said to combine with anthocyanins to deepen color and improve the structure of wine.
Being a tannin, it gives a slight astringency, but it is very gentle compared to condensed tannins derived from seeds and skins.
When you feel slight astringency in white wines that have undergone barrel aging, it can be considered related to the extraction of this ellagitannin. (When short-term maceration has not been performed)
Coumarin
Coumarinis a flavor compound with such a charming name, but when there is too much of it, it gives a strong bitterness to wine.
It is said to be rarely extracted into wine, but since the amount of coumarin changes depending on the drying conditions of the barrel wood, excessively bitter wines that have undergone barrel aging may be related to coumarin.
In very small amounts, it is thought to have a favorable influence on the structure and flavor of wine.
Let's pay attention to barrel use
There are still many more flavor compounds that influence the flavor of wine.
This time, I introduced the representative ones, so please remember them.
Now, in recent years, the number of producers who don't want to give these influences to wine has been increasing, and there are even producers who useold barrels, large barrels, or no barrels at all.
There is a tendency to value the original aromas and flavors of the grapes, sowines with excessive barrel influence are becoming less common worldwide..
Japanese wine in particular is delicate, so wines overly influenced by barrels are rarely seen. (A while ago, there were many such wines)
From now on, it might be interesting to drink wine while thinking about how much barrel influence is present.
Please give it a try.
References
Fascinated by Barrels and Oak: Gifts of the King of the Forest (Quercus), Whisky, Wine, and Mountain and Sea Delicacies
Sadahiko Kato (author), Katsuhiko Yoshida (illustrator)