TANNIN-PROTEIN INTERACTION IS MORE CLOSELY ASSOCIATED TO ASTRINGENCY THAN TANNIN-PROTEIN COMPLEX PRECIPITATION

Abstract

For Review. Confidential The relative abilities of two enological tannins to interact with a single gelatin were compared with their relative abilities to elicit astringency. A trained sensory panel assessed astringency whereas the interaction between tannins and gelatin was estimated by observing the ability of tannins both to interfere with gelatin diffusion on a cellulose membrane and to form tanningelatin precipitates. HPLC chromatography and spectroscopic analysis showed that one of the tannins was hydrolysable tannin while the other one was a proanthocyanidin. The majority of the sensory panelists recognized the hydrolysable tannin as far more astringent than the proanthocyanidin. Finally we showed that the more astringent tannin interfered markedly with gelatin diffusion on the cellulose membrane but it failed to produce tannin-gelatin precipitation whereas the proanthocyanidin tannin both interfered with gelatin diffusion and was a powerful gelatin-precipitant. Thus, this study supports the hypothesis that astringency correlates better with gelatin-tannin interaction than gelatin-tannin precipitation.