ESTIMATION OF MUST OXIDATION DURING PRESSING IN CHAMPAGNE

Chardonnay and Pinot noir musts obtained in Champagne wineries using c ommercial pressing equipment were sampled at regular intervals through out the pressing cycle. Their phenolic compositions were monitored by HPLC and compared with those of musts prepared from the same grapes an d oxidized under controlled conditions. Important oxidation occurred i nside the press. At the beginning of pressing, must oxygen consumption was estimated at 300 to 400 mu moles per liter. The musts obtained at the end of pressing contained larger amounts of phenolic compounds bu t were also highly oxidized. Sulfiting under enological conditions (50 mg/L) reduced the quinones present so that oxidation was partly rever sible. The extent of oxidation and extraction depended on the kind of press used but also on pressing management, in particular on the time allowed for pressing.