In my quest to learn more about wine, I have been researching the role of oak in wine making. Why, you ask? Well, I love wine and want to understand more about what factors contribute to a wine being one that I love vs. one that I could see go down the drain. To me, wine making is similar to cooking. One has a set of ingredients available and some learned techniques to employ and viola! A wine (or meal) is made. Keeping up with this analogy, the grapes are the main ingredient in the dish. Oak is a seasoning. Anyone who cooks knows that the use of seasoning can be an amazing enhancement to your meal, or when used incorrectly, its ruin.
What do I mean by oak anyway? Oak is a tree that is used makes wood products, which I assume everyone knows. Wine can be fermented and stored in oak barrels, and the extent to which that happens affects the wine considerably. My research has led me to conclude that many wine makers have tried to make wine using barrels from other kinds of wood, however, oak is simply the best. Why? It allows the wine to slowly evaporate as it is slightly porous, therefore concentrating its flavors without allowing much oxygen exchange that could ruin a wine. It also imparts flavors and tannins to the wine that may enhance its taste and aroma. And, aging wine in oak enables a very tannic red wine too mellow out, also considered an improvement.
These all sound like great things, right? So why wouldn’t every winemaker go to town with oak? Well, it brings me back to the cooking analogy. Imagine a great cut of steak or a thick slice of ripe tomato. Perfectly seasoned it is heaven on earth. But pile on way too much salt and use too much of a spice like cumin which could overpower the flavor of the food, and it is ruined. In my opinion, some wine makers overdo the use of oak, which I think it akin to using too much salt on food (I definitely like a my food seasoned but there is definitely such a thing as too much salt).
Wine makers, like chefs, have options regarding their use of oak. Some ferment their wines in oak barrels. Some age (or mature) their wine in oak barrels. The latter technique will lead to more oak influence because in the former, the yeast used in fermentation will absorb some of the oak flavors. The yeast gets tossed so those flavors get tossed. I hope to learn more about what conditions lead a winemaker to decide to use oak for either stage.
Winemakers in Europe have used oak barrels in their winemaking for centuries. This technique started in the US in the 60s led by wine pioneer and innovator Robert Mondavi (side note, when I was a freshman in college, my roommate who was in the hotel school (at Cornell where we went) was over the moon one day because Robert Mondavi spoke at one of her classes. She was giddy which I clearly remember, however, I had no idea who he was. I wish I had seen him speak as he really was an amazing influence on wine making in America).
The oak used to make wine barrels is grown in primarily three places; France, the US and Eastern Europe (Hungary & Slovenia). The wood itself varies due to the differing soil and climate, however, the techniques used to make the barrels also differ. In France, the wood is split along the grain to make the staves and in the US, saws are used. This leads US wood to have a more pungent oak aroma. The staves are aged and seasoned outdoors for an extended period of time in France and in the US kilns are used. As a result, the taste and tannic influence of American Oak is greater on a wine than French Oak. Some wine makers appear to prefer one over the other. Again, I want to learn more about what makes a winemaker choose a particular kind of oak barrel for their wines.
Different varietals, or grapes, are aged in oak for various lengths of time. Lesser tannic wines like Pinot Noir typically spend less than a year in oak. Cabernet which has much more tannin could spend up to 2 years in oak. And very tannic wines like those made from Nebbiolo (the grape in Italian Barolos) would spend upwards of 4 years aging in oak barrels before bottling.
An oak tree typically grows for 80-120 years before harvest and one tree is needed to make two 59 gallon barrels. Wow. Talk about a deterent if a winemaker was hoping to save some money by growing their own oak trees for barrels.
Now on to how the use of oak influences the taste of wine. The tastes in wine that are spice-like are influenced by oak; vanilla (easiest for me to spot), caramel, coconut, mocha and butter. The nose, or the smell of the wine, is also an indicator of oak use. Aromas of clove, cinnamon, nutmeg and allspice are oak driven.
The barrels are toasted prior to usage. Toasting is literally cooking the inside of the barrel via high heat or fire, like toast made from bread. The level of toast is classified as light, medium and heavy. I was surprised to learn that medium and heavy toasts are used for white wines and bourbon, as this level of toast can adversely affect the color of red wines. Consequently, light toasts are used primarily for red wines.
Conclusions? Oak is a valuable tool in wine making to enhance the taste of wines, and and allow it to concentrate as it ages. The lovely aromas and tastes of spices and wood can also make a wine better by increasing its complexity. However, too much oak and the resulting flavors (especially vanilla) can overpower the taste of the fruit (in my opinion). Like using salt to season food, oak when used judiciously can lead to wonderful wines but too much is too much.
Please feel free to comment or clarify if I am wrong on any points, or you have additional information regarding the use of oak in making wines. I still have much to learn on this fascinating subject!