Around the time of the Mesopotamians, oak barrels were used to store wine. It was not until the Roman Empire that winemakers gradually realized that oak barrels were not only used to store and ship wine, but also had an impact on wine. So what are the effects?

Oak barrels have been used in wine storage and aging for more than 2,000 years. For a long time, winemakers have known that oak barrels can not only highlight the original fruit aroma of wine, but also infuse the aroma and tannin of oak itself, which makes the wine taste better. supple, complex in its flavors, but also in a more balanced structure.

In addition to determining the length of time the wine is aged in oak barrels (months to years), the winemaker will determine the different oak varieties, the degree of roasting at the time of manufacture, and the size of the oak barrels. Even old and new barrels, etc., have a decisive influence on the style of the final wine. The longer it is aged in oak barrels, the heavier the oaky will be (too long and it will overshadow the fruit). Common Australian wines use a mix of French and American oak barrels. French oak barrels are generally believed to give wines lemon, citrus and nutty flavors; American oak barrels give wines sweet, vanilla and malt flavors.

1. Flavor and Tannins

The grape variety itself can bring a certain amount of tannin to the wine, and during the maceration process, the longer the grape skins are in contact with the grape juice, the higher the tannin content of the wine. For varieties that do not have too much tannin themselves, oak aging can also bring tannins, and new oak barrels bring more tannins than old oak barrels. The flavor that oak brings to the wine also varies according to the degree of toasting in the oak barrels. This flavor can be a vegetable aroma or a strong vanilla and spice flavor. With the same wine grapes, oak-aged and unoaked wines can be very different.

2. Phenolics

Many people have heard the term phenolics, but don't know what they are. Essentially, phenolics play a very important role in the aroma and flavor of wine. When phenolics in wine come into contact with oak barrels, new compounds are formed.

3. Oxidation

When wine is stored in a closed environment, the probability of oxidation is very low. However, the oak barrels themselves are breathable, which allows a small amount of oxygen to penetrate into the barrels and conduct a slow and subtle oxidation with the wine, which in turn affects the aroma and flavor of the wine. Wines that have been aged in oak barrels for a long time often require this small amount of oxygen to mature, but too much oxygen can undoubtedly have negative effects.

4. Evaporation

Many people are unaware of the fact that for every 59 gallons (223 liters) of wine on average, nearly 6 gallons (about 23 liters) evaporate each year. During the oak aging process, although winemakers will compensate for the loss caused by evaporation by injecting new wine, it will inevitably have some impact on the flavor of the finished wine.