Publication | Closed Access
Influence of Fining with Different Molecular Weight Gelatins on Proanthocyanidin Composition and Perception of Wines
109
Citations
0
References
2001
Year
Food ChemistryProanthocyanidin CompositionFlavoromicsBiochemistryWine StudiesCondensed TanninsFood AnalysisTanninCommercial GelatinWine TastingRipeningFood QualityPrecipitation ProcessPolyphenolicsHealth Sciences
Fining treatments clarify wine and are reported to reduce astringency. The study compared the fining efficiency of commercial gelatin and two gelatin‑derived fractions (≈16 000 Da and ≈190 000 Da) across four wines with varying tannin profiles. Gelatin fining removed about 10 % of tannins, preferentially the highly polymerized, galloylated ones, while non‑proanthocyanidin polyphenols remained in solution; the resulting lower tannin levels in the treated wines likely explain the observed reduction in astringency.
Fining treatments are an important step in enology as they allow clarification and are reported to decrease the astringency of wines. Fining ability of a commercial gelatin and of two different molecular weight proteinaceous fractions derived from it (averaging 16,000 and 190,000 daltons, respectively) were studied in four wines with distinct composition of condensed tannins. The non-proanthocyanidin polyphenolic compounds did not precipitate with gelatins. The more polymerized and galloylated tannins were selectively precipitated, but the amount of epigallocatechin units was not significantly different from that of tannins of the corresponding wines. This observation suggests the important role of the number of accessible <i>o</i>-diphenolic and <i>o</i>-triphenolic rings in the precipitation process. The percentages of precipitated tannins were equal for the two fractions of gelatin studied (about 10%), while the tannins precipitated by the lower molecular weight gelatin were more polymerized than those precipitated by the higher molecular weight protein. The percentages of precipitation for the whole gelatin seem to be more dependent on the composition of wines, but in most cases the gelatin precipitated more tannins than the fractions (from 11 to 16%). The supernatants (treated wines) were significantly lower in tannins than the corresponding wines, suggesting that the reduction of astringency may be linked to the decrease of tannin concentration in fined wines.