Tannins protect wine from oxidation during barrel aging. The wood tannins extracted from a new barrel protect the wine from over-oxidation during the slow process needed for tannin polymerization and wine development. When using old barrels, indigenous
tannin may have been completely leached out. A small tannin addition of 5-10 g/ hL of Tannin Estate or Tannin Refreshwill act as an anti-oxidant and help protect the wine. Attaining a good phenolic profile will slow the maturation process and still protect the wine.