Definition: Copeaux

However, the use of oenological tannins has recently been authorised. Produced from gallnuts (growths on the leaves and young shoots of oak trees), this tannin-rich powder is used during the fining of wines to limit the action of the fining proteins, which cause the particles suspended in the wine to precipitate to the bottom. Excessive fining often has a negative effect, as it strips the wine of its substance. This is precisely where oenological tannins come in, as their action is to reconstitute weaker wines that would not withstand fining.

In conclusion, the use of "barrel substitutes", which cost ten to fifteen times less than a barrel, should be prohibited for the production of quality wines that claim to express a terroir. Only the barrel is capable, in addition to tannins, of providing the wine with a constant, tiny dose of oxygen that promotes perfect maturation.