Oxygen exposure during red wine fermentation modifies tannin reactivity with poly-l-proline

Food Chem. 2019 Nov 1;297:124923. doi: 10.1016/j.foodchem.2019.05.197. Epub 2019 May 30.

Abstract

Red wines injected with nitrogen or oxygen during fermentation were used to identify the effect of gas exposure on tannin structure and reactivity with poly-l-proline. Tannin was purified from wine after fermentation and after three years of bottle storage. Tannin from nitrogen-treated wine had a lower percentage of galloylation and were less pigmented than tannin from oxygen-exposed wine. Self-aggregation of tannin was measured by nanoparticle tracking analysis and a larger particle size was observed for the oxidized treatment. The interaction of tannin and poly-l-proline was measured by isothermal titration calorimetry, and involved more hydrogen bonding than hydrophobic interactions in the case of nitrogen-treated wine tannin. Conversely, oxidized tannin was more hydrophobic and the association with poly-l-proline was entropy-driven due to a change of solvation. The results show meaningful changes in the structure and reactivity of tannin as a result of oxygen exposure during fermentation, which may impact astringency perception.

Keywords: ITC; NTA; Oxidation; Particle size; Proanthocyanidins; Thermodynamic parameters.

MeSH terms

  • Bioreactors
  • Calorimetry
  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions
  • Oxidation-Reduction
  • Oxygen / chemistry*
  • Particle Size
  • Peptides / chemistry*
  • Tannins / analysis
  • Tannins / chemistry*
  • Thermodynamics
  • Wine / analysis*

Substances

  • Peptides
  • Tannins
  • polyproline
  • Oxygen