Chemiluminescent determination of total antioxidant capacity during winemaking.

The total antioxidant capacity (TAC) of five different wines (four red and one white) was determined in five different steps of winemaking carried out in a commercial wine cellar by a chemiluminescence (CL) assay. The CL method is suitable to determine the antioxidant capacity of beverages, and preliminary trials showed that the TAC immediately after the bottle was opened was greater than the day after (about 25% decrease). Immediate analysis or a correct sample storage is therefore necessary. The wines were characterized by different levels of total phenolics and TAC: these differences were related to grape composition and winemaking technologies. The TAC values were the highest immediately after devatting. The TAC suffered the highest decrease (30-50%) after the clarification procedure, which may be due to the fining agents used and to oxygen contact, then remained more or less constant in the subsequent steps. Copyright 2006 John Wiley & Sons, Ltd.