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Knowledge enhancement | So much knowledge about oak barrels!


(Photos/Texts | Yantai Shenma) 

After being stored in oak barrels, the wine will feature more complicated flavor and better taste! The benefits brought to wine by oak barrels including clarifying, color stabilizing, tannins softening, body and complexity enhancement, flavor adding (new barrels), ripening accelerate, reduction of the aroma of herbs in certain wines, reduction risk reducing, etc.


As a good friend of wine, how does the oak barrel affect the wine? Let us unlock the secret of the oak barrel from different perspectives!



· The source of oak barrels


1.    The history of oak barrels dates back to 2690 BC, but sealed oak containers (such as oak barrels) did not appear until 800-900 BC, when they were used to store olive oil and honey in addition to wine.


2.  Oak barrels were not originally used for the ripening of wine or spirits. The ancient Romans once used bulky binaural pots with narrow necks to transport the wine in large quantities; and they did not discover the benefits of using oak barrels to transport beer until they invaded Gaul. At first, the Gauls only used the oak barrels as a tool for transporting the wine. When the benefits of storing wine in oak barrels began to appear, the techniques of using oak barrels to ripen wines gradually emerged.





· Types of oak


There are up to 250 types of oak, and the common oak used for barrels are the Quercusalba in the United States and the Quercusrobur in Europe.


1.   Quercusalba: Oak (Xiangmu) is a common name, and its scientific name is (yuè) wood; quercus, it is widely used in the whisky industry because of historical reasons in addition to the good quality. After the Second World War, in order to promote the continuous development of the oak barrel industry, American barrel makers urged legislation to stipulate that BourbonWhisky must be ripened in new oak barrels. Therefore, a large number of high quality and inexpensive Bourbon Cask came into being.


2.    European Oak: also known as Quercus robur, British Yue, European Yue, with more tannins and more tannic acid. Due to the limited supply of European Oak, American Oak has also become main materials for the manufacture of Sherry Cask.


· The origin of oak


Bordeaux, Burgundy, Piedmont... We are familiar with these world-class wine regions. For oak, the origin is also very important, and the quality of woods in different forests different a lot. European Oak is widely cultivated; it reaches the Ural Mountains in the east, France in the west, Norway in the north, and Sicily in the south. 

Some oak forests in France are recognized as the best, and the price is also the most expensive. The most famous ones include Troncais, Allier, Nievre, Vosge, Limousin, etc. The oaks produced different forest areas have their own characteristics. The oaks in Eastern Europe are mainly from Hungary and Slavonia, very cost effective. Many large wooden barrels in Italy are made of Slavonia oak. Some people think that these oaks contain too much tannins for French varieties such as Cabernet Sauvignon and Pinot Noir, and they are more suitable when matched with Sangiovese and Nebbiolo. Portugal also produces a small portion of oak, mainly from the north; if properly processed, they can be used as a cheap alternative to French oak. 

Most of the raw materials for American oak barrels are produced in Minnesota, Lowa, Oregon, and Wisconsin. Some people think that the Quercus alba of Minnesota and Wisconsin is most suitable for oak barrels, and the tannins contained in oaks from other forests are too much. 

Quercusrobur differs a lot with Quercusalba when it comes to attributes. Take the French oak as an example, many of the oak forests in France date back to the Napoleonic period. In the colder climate in France, the oak features a long growth cycle and a finer texture. While the Quercusalba has a relatively short growth period and comes from different forests. In terms of processing methods, French oak barrels are generally cut according to texture, and the utilization rate is low (about 20%); while the utilization rate of oak in American oak barrels reaches as high as about 50%. 

· The effect of oak on wine or spirits


The effects of oak on wine or spirits vary, depending on different chemical composition contained in the different oaks; whether the inside of the oak barrels is carbonized and the degree of carbonization; the amount of oxygen in the oak barrels; the type of spirits or wine, etc.

 

· The baking degree of oak barrels

 

Most oak barrels go through baking processing (there are also oak barrels not), which changes the physicochemical structure of the oak and thus affects the style of the wine. By controlling the time and power of heating, the baking degree can usually be divided into three levels (four levels for some barrel makers):

Lightly-baked barrel: baked for 5 minutes at a surface temperature of 120–180 ° C; the color of the barrel wall changes a little, and the aroma of the ripened wine inside is not affected too much; more tannins can be gained from the lightly baked barrel, making the wine itself fruitful, but it may be bitter. 

Medium-baked barrel: baked for 10 minutes at a temperature of 200°C; the color of the barrel wall becomes browner, and the ripened wine inside will have a sweet vanilla and coffee flavor. The tannin is softer than the former, which is round and smooth on the whole.

Heavy-bake barrel: Baked for 15 minutes at a temperature of 225°C; the color of the barrel wall is very dark, and the ripened wine inside will have flavors featuring obvious roasted coffee beans, toast, bacon and many mild spices.

Baked oak also acts as a buffer between alcohol and oak tannins. The lower the baking degree, the more tannins entering the wine, and this is the reason why the lightly-baked barrel makes the wine taste more woody (oaky/woody). Burgundy oak barrels are usually baked slightly heavier than Bordeaux oak barrels, as Chardonnay and Pinot Noir are more suitable for soft oak tannins than Bordeaux varieties.