Role of melanoidins in sweet wines

Melanoidins from several Spanish sweet wines were isolated by dialysis. Browning indexes (absorbances at 420 and 345 nm) and CIELab parameters of the wines and their dialysed fractions were measured. The antioxidant activity, which was expressed as Trolox equivalent antioxidant activity (TEAC), was determined using the N,N-dimethylphenylene diamine dihydrochloride (DMPD) method. Results showed a good correlation of colour parameters L*, h* and absorbances at 345 and 420 nm between the dialysed fractions and the original sweet wines. However, the TEAC of dialysed fractions did not show any significant correlation with TEAC of the original wines. So brown polymers of high molecular weight (>12000 Da) isolated by dialysis, which could be mainly melanoidins, play an important role on the colour of these sweet wines, but not in their antioxidant activity. (C) 2002 Elsevier Science B.V. All rights reserved.