Effect of skin contact and oxygenation of musts on the composition of white port wines

White port wines were made from Malvasia Fina and Rabigata grape musts that were subjected to different combinations of skin contact and must oxygenat ion. Increasing skin contact times increased the total phenolics, total hyd roxycinnamoyl tartaric acids, total flavonoids and the formation of brown p igments in the free-run musts. Both air exposure and hyperoxidation were ef fective in lowering the concentration of hydroxycinnamoyl tartaric acids an d flavonoids in newly fermented wines. Hyperoxidation seemed more effective in removing these phenolic compounds and in reducing browning than air exp osure in wines which had 8 and 25 h of skin contact. Phenolic compounds inc reased with wood ageing, although the concentration of hydroxycinnamic acid s were lower in all oxygenated wines than in the controls. However, must ox ygenation prior to fermentation could not prevent further browning of the w ines caused by the production of furans, and the increase of flavonoids dur ing their ageing in wood. Increasing skin contact generally increased the t otal monoterpene alcohol concentration for hyperoxidised wines, with some i ncreases in air exposed wines. Total monoterpene alcohol concentration was higher in hyperoxidised than in air exposed wines, made from musts with 8 a nd 25 h of skin contact, after 18 months of wood ageing.