According to the history of British winemaking, in the17th century, in order to resist the malt tax levied by the government, British winemakers made oak barrels of different sizes, put all the wines into oak barrels and stored them in caves. A year later, they took out the bucket and a miracle appeared. They found that the color of the wine turned golden yellow, and the taste of the wine was extremely mellow, accompanied by a fragrance that had never been seen before. After careful study, it was found that it was the peculiar function of oak barrels, because oak itself contained "tannic acid", which could make wine mature quickly and become more mellow and amber in a short time. As a result, wine storage in oak barrels came into being.