Changes in Phenolic Compounds and Colour Parameters of Red Wine Aged with Oak Chips and in Oak Barrels

Changes in phenolic compounds and colour related parameters of a red wine, Cigales Appellation of Origin, were monitored during its ageing in oak barrels and with added oak chips. Results were statistically analysed by multifactor analysis of variance and discriminant analysis. The wine aged in contact with oak chips underwent a quicker ageing, their loss of anthocyanins was also faster and suffered a higher number of polymerisations than the wine aged in barrels. Red wine colour changed during ageing due to the contribution of yellowish pigment compounds, which differed depending on how the oxidative ageing took place, and by the increasing stability of the blue co-pigments. The discriminant analysis showed that samples of the same source wine aged in barrels and with oak chips tended to be grouped together according to ageing system.

Determination of free molecular phenolics and catechins in wine by solid phase extraction on polymeric cartridges and liquid chromatography with diode array detection

The use of HLB Oasis polymeric cartridges to extract phenolic acids and aldehydes from red wines has been assayed and compared with the combination of ODS and SAX cartridges. The recoveries on the polymeric cartridges resulted to be notably higher with good precisions. The best operation conditions (cartridge conditioning, sample volume, clean-up and elution) for these latter were selected by experiments carried out on a synthetic wine sample spiked with 14 compounds and on red wine samples. A matrix-matched calibration was advisable to reduce the influence of the matrix in the quantification of the analytes as it was verified from the application of standard addition calibrations on several wine samples. Determination of the analytes in the extracts was performed by reversed-phase HPLC using mobile-phase and flow gradients and detection at 250, 280 and 340 nm.