Colloidal behavior of wine galloylated tannins

Tannins are one of the four key components determining wine organoleptic quality. First, they play an important gustative role since they are responsible for wine astringency and/or bitterness. Second, they act as a structuring compound directly linked to red wine turbidity and stability. This second role is the consequence of their colloidal behavior. In the present work, we demonstrate that wine tannins exhibit different colloidal behaviour whether they are or not galloylated. Procyanidins, when galloylated, are more inclined to form micelles than their non-galloylated form, letting us suggest that they could act as structuring agent in wine. However, the size of the formed micelles is of the nanometer range suggesting that procyanidins, up to trimers, are not involved alone in wine turbidity. (C) 2009 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.