Effect of Pomace Contact and Hyperoxidation on the Phenolic Composition and Quality of Grenache and Chardonnay Wines

Abstract

Several lots of Chardonnay and Grenache blanc grapes were treated with pomace contact and/or hyperoxidation prior to clarification and fermentation. Changes in wine phenolic composition and browning susceptibility due to these prefermentation treatments are reported. Pomace contact wines contained larger concentrations of caftaric acid and flavans but lower amounts of 2-S-glutathionyl caftaric acid and were more susceptible to browning. Hyperoxidation induced losses of all phenolic constituents and increased wine resistance to browning. Variations in the chemical and sensory properties were examined by principal component analyses. Browning was highly correlated with the amount of flavans and especially procyanidin B1. Other compositional attributes were not affected by prefermentation treatments except for absorbance at 280 nm which was correlated with caftaric acid content and higher in pomace contact wines and for absorbance at 420 nm which increased with hyperoxidation. From the PCA of the sensory data, pomace contact appeared beneficial to Chardonnay wines and detrimental to Grenache wines. Hyperoxidation did not modify the wine sensory properties. It was successfully applied and may be of interest to avoid the undesirable browning resulting from phenolic extraction during pomace contact.