[Rivista ISI; Impact Factor (2009)=2,469; Riviste nella categoria=118; Posizione nella categoria=10; Quartile=Q1; Mediana=0,9; Primo autore e Autore corrispondente] Short abstract. A first attempt at a semiquantitative study of molecular weight (MW) and molecular weight distribution (MWD) in cooked grape must and traditional balsamic vinegar (TBV) with increasing well-defined age was performed by high-performance liquid size exclusion chromatography (SEC). Compositionally and structurally heterogeneous blends of melanoidins were recognized as copolymers ranging from 2 to over 2000 kDa. The distribution parameters of polymeric melanoidins varied with time and asymptotically toward either upper or lower limits: they were proposed as aging markers of TBV.