Preliminary study on the interaction of gelatin-red wine components

Physico-chemical parameters of two oenological gelatins (G1 and G2) were ex amined to investigate the interaction of protein-wine components during the fining of red Sangievese wine. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) was used to analyze the molecular weight distrib ution (MWD) of the two gelatins. The differences in the gelatins are primar ily due to the manufacturing method. In particular, gelatin G2 showed the g reatest reduction in MWD as a result of the atomization process. Moreover, G1 and G2 differed greatly in net charge density (0.94 and 0.12 meq/L, resp ectively) and Bloom strength (75 and 0 g, respectively). The implications o f these observations on the mechanism of gelatin-wine components interactio n in wine are discussed. Increasing amounts of gelatin were added to Sangio vese red wine at controlled temperatures and the efficacy of the fining tre atment was evaluated in terms of turbidity and the amounts of precipitate d eveloped. Both gelatins were able to interact with wine polyphenols and the amount of precipitate increased from 0 degrees>30 degrees>15 degrees C. Th e amount of precipitate increased with gelatin dosage. We postulate that wi ne components other than polyphenols (e.g., tartrate microcrystals, protein and/or polysaccharides) may co-precipitate with gelatin during the coagula tion process.