Interactions of tea tannins and condensed tannins with proteins

Summary

This in vitro study characterised the binding interactions between four chemically distinct tannin types (tea catechins, grape seed and mimosa proanthocyanidins, and sorghum procyanidins) and two model dietary proteins (gelatin and bovine serum albumin) using isothermal titration calorimetry. Binding affinity varied substantially by tannin type and protein substrate, with sorghum procyanidins binding most strongly to gelatin and all interactions being exothermic with multiple binding sites. The findings provide mechanistic insight into how tannin structure relates to protein-binding capacity, which is relevant to understanding tannin bioavailability and nutritional effects.

Regional applicability

This is a fundamental biochemistry study with no specific geographic context; findings on tannin–protein interactions are universally applicable and relevant to United Kingdom dietary guidance on polyphenol-rich foods (tea, red wine, legumes). The mechanisms identified could inform plant breeding and food formulation strategies in UK agriculture.

Key measures

Equilibrium binding constants (M⁻¹), enthalpy change (kcal/mol), number of binding sites, assessed via isothermal titration calorimetry

Outcomes reported

The study quantified binding parameters (equilibrium constants and thermodynamic properties) for interactions between four types of tannins and two model proteins using isothermal titration calorimetry. Sorghum procyanidins showed the strongest binding to gelatin (10⁴–10⁶ M⁻¹), whilst tea catechins showed the weakest; interactions with bovine serum albumin were generally weaker across all tannin types.

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