CHARACTERIZATION OF (-CATECHIN-ACETALDEHYDE POLYMERS - A MODEL FOR COLLOIDAL STATE OF WINE POLYPHENOLS())

The (+)-catechin-acetaldehyde condensation was studied as a model for tannin polymerization and precipitation in red wines. It was shown by using LSIMS that reaction products are catechin polymers with CH-CH3 b ridges at two reaction sites. Before the end of monomer conversion int o polymers there is an aggregation followed by a phase separation. Par ticle mean diameter was measured by dynamic light scattering directly in reaction medium. Comparison between particle and polymer sizes show ed that polymers aggregate into colloidal intermediates before a large polymerization degree is reached. These particles then coagulate furt her, which leads to polymer precipitation. This colloidal behavior is explained by hydrophobic forces since aggregates and precipitate redis solve in ethanol.