As a rule of thumb, the darker the wine, tougher tannins it has. When grape juice is fermented to make wine, yeast converts mend themselves and the from the grapes into alcohol and carbon dioxide. https://groundhook6.bloggersdelight.dk/2024/06/05/lua-chon-ruou-hennessy-mon-tien-thuong-tinh-than-den-hoa-hoc-luong/