Where do all those nifty flavors come from in wine?
"My wife and I have a question about wine and how Reds get all of their flavors of fruit, chocolate, tobacco, vanilla, etc. I understand that some of the flavoring comes from the barrel and the earth, but how about all the unique flavors that are used today? We are only becoming regular wine drinkers and someday would like to understand what we are consuming."
My answer is, as usual, rather long and detailed, but important enough that I wanted to share it with everyone.
Wine is made from grapes, and it is sometimes aged in wooden (usually oak) barrels. Nothing else is added (sugar and acid can be added in some parts of the world, but not usually to quality wines).
All of the flavors you taste come either from these sources, or from the fermentation process itself.
Part of the problem in talking about wine are these very subtle flavors you mention. Not only are they subtle, but they are highly subjective. What may taste like chocolate and tobacco to you, may just as easily taste like leather and tar to someone else. It is for this reason that I teach in my courses and in my book to acknowledge these flavors to yourself, but to talk more about the objective balance of the wine. Is it tart? Is it rough? These are much more universal sensations, and ultimately mean more about the quality of the wine.
I suspect all of the flowery language (what I call the fruit basket syndrome) was started by wine writers that get paid by the word.
All of that aside, some things, like vanilla, butter, and even leather, have very distinct chemicals that are responsible for their being found in wine.
Vanilla (vanillin is more exact) comes from the vanillic acid found in oak (this is where artificial vanilla flavor comes from).
Buttery notes in wine are due to the presence of diacetyl (the chemical added to vegetable oil to make margarine taste like butter) which is a byproduct of a secondary fermentation called malo-lactic fermentation (which is often induced in wines to soften the acidic taste).
Leather is one of my favorite aroma/tastes to talk about. Raw hide has no smell. Pick up a doggy chew toy and this is easy to determine for yourself. Leather is "tanned" in order to preserve it. The tanning agent is "tannin" itself, one of the major components of red wine (along with fruit, and acidity). When you smell or taste leather in wine, it is due to the tannin.
Other common aroma/flavors, such as caramel, and certainly almost all the "off" odors, also come from chemicals that are a by product of the wine making process.
The fruit flavors, and other subjective elements of the wine have more to do with the fact that the brain likes to find patterns, and will impose a pattern when none is found, than due to any actual components found in wine. Smell is one of the strongest triggers of memory, so when you smell wine, your mind is busy trying to remember what all those smells are.
Different grape varieties tend towards one or more of these subjective aromas. For example most Pinot Noirs have a sense of cherry about them. Cabernet Sauvignon can smell of currants, and Merlot can have a green bell pepper character. Wine making, the region where the grapes are grown, and how the wine was handled will all have an effect on the final product, and a Cab from one producer may not have any resemblance to a Cab from another producer.
My advice is to enjoy the smells and tastes without worrying too much if you "get them right," at least until such time you decide you want to learn to "read" a wine. This skill encompasses not only knowing what subtle aromas to look for, but what clues color and aspects of the wine can tell you about how it is made and how it stacks up against other wines of similar provenance.
When you do want to learn how to read a wine, come take my course. I am one of the few in the world that specialize in teaching this skill, even though I consider it to be more of a parlor trick than a necessary part of a wine education.