Composition and analysis of colloidal matter along wine-making. Exploitation of its antioxidant activity in final stabilisation residues

Colloidal matter formed along vinification has been characterized for two consecutive vintages in order to a better understanding of the final solid residues obtained by freezing stabilisation. The polyphenolic content, metal concentrations and antioxidant activity of these residues have been determined. Vintage 2003 of a Vitis vinifera (Tempranillo variety) yielded a concentration of 19.018 ± 0.226 mg g− 1 of total anthocyanins (TA) and 13.258 ± 0.158 mg g− 1 of total flavonoids (TF) in fresh deposits. It has been found that ca. 50% of initially present Fe is eliminated along wine-making, only 6% of Cu ends up in final wine and all Mn present at the beginning of the process remains in commercial wine. Antioxidant activity in the residues is found to be related to total polyphenol concentration irrespective of polymerisation degree. An EC50 of 0.130 ± 0.007 g L− 1 (g of lyophilised dreg per L of buffered solution) was obtained for vintage 2004. Antioxidant capacity of different fractions of wine was not seen to depend upon addition of metals.