Effect of Pomace Contact, Carbonic Maceration, and Hyperoxidation on the Procyanidin Composition of Grenache blanc Wines

Lots of Grenache blanc grapes (Vitis vinifera) were submitted to a pomace contact or carbonic maceration and/ or hyperoxidation prior to clarification and fermentation. Changes in several classical wine analytical parameters and wine phenolic composition, including the procyanidin composition, are reported. Wines were purified on a polyamide chromatographic column. A procyanidin fraction was thus obtained and further analyzed by reversed-phase HPLC. To our knowledge, procyanidins trimer C₁, trimer 2 [epicatechine-(4β -> 8)-epicatechin-(4β -> 8)-catechin], B₁ 3-0-gallate, B₂ 3-0-gallate, and B₂ 39-0-gallate were quantified for the first time in white wines. Carbonic maceration wines contained larger amounts of procyanidins, followed by the pomace-contact wines. Hyperoxidation induced important losses of all phenolic compounds analyzed. When its quantification was possible, procyanidin B₁ was the major procyanidin in Grenache blanc white wines, although trimeric procyanidins were also present in important amounts. The galloylated-dimeric procyanidins were minor components in white wines.