Biology Reference
In-Depth Information
Whether or not all of these oak-derived
C
-glycosidic ellagitannins
significantly contribute to the organoleptic qualities of wine still remains
to be determined. The question of whether oak ellagitannins have an
effect on taste characteristics has been and still is subject to debate in the
literature (Vivas and Glories, 1996). Some authors suggest that the
presence of oak ellagitannins can account for much of the astringency
and bitterness of wine aged in barrels, whereas others believe that their
concentration is too low to contribute to these taste characteristics (Quinn
and Singleton, 1985, Somers, 1990, Hervé du Penhoat
et al.
, 1991b,
Pocock
et al.
, 1994, Puech
et al.
, 1999a). Besides our own contributions
and earlier ones notably by Puech and associates toward a better
molecular-level understanding of the chemical reactivity of oak
ellagitannins during cooperage and wine oak-maturing processes,
Hofmann and Glabasnia have recently invested efforts in this field, and
identified new “taste-active” vescalagin and castalagin deoxy- and
dehydroderivatives (Fig. 9.18).
Some of these derivatives (
i.e.
,
49
-
50
), as well as their vescalagin (
1
)
and castalagin (
2
) parents, were found to impart astringent mouth-coating
sensation at remarkably low threshold concentrations comprised between
1 and 4 mg/L (Glabasnia and Hofmann, 2006, 2007). So, the debate on
the contribution of oak-
versus
grape-derived polyphenols to the
organoleptic properties of wine will certainly go on, but it may turn in
favor of a reappraisal of oak polyphenols in view of the growing
development of alternative wine-aging practices based on the use of
(toasted) oak chips and micro-oxygenation treatments (Garde-Cerdán
and Ancín-Azpilicueta, 2006).
Acknowledgements
We gratefully acknowledge funding from the Conseil Interprofessionnel
du Vin de Bordeaux, the Conseil Régional d'Aquitaine and the Agence
Nationale de la Recherche (ANR-06-BLAN-0139). We deeply thank our
colleagues from the Faculté d'Œnologie at the University of Bordeaux,
Prof. Yves Glories, Dr. Cédric Saucier and Prof. Pierre-Louis Teissedre,
for their input and advice.
