Pb and Cu speciation and bioavailability in port wine

Area of Science:

• Food Chemistry
• Environmental Chemistry
• Toxicology

Background:

• Port wine contains lead (Pb) and copper (Cu), essential to assess human bioavailability.
• Metal speciation influences metal absorption and potential toxicity.
• Understanding metal-ligand interactions in wine is crucial for dietary exposure assessment.

Purpose of the Study:

• To investigate the speciation of Pb and Cu in various Port wine types.
• To estimate the bioavailability of Pb and Cu through in vitro simulated gastrointestinal digestion.
• To determine metal distribution and complexation across different wine matrices and digestion stages.

Main Methods:

• In vitro simulated gastrointestinal digestion of Port wines.
• Potentiometry and cathodic voltammetry to determine metal complex stability constants (K(av), K'(av)) and ligand concentrations (CC, CC(inert)).
• Reverse-phase high-performance liquid chromatography (RP-HPLC) for metal distribution analysis based on molecular weight and polarity.
• Quantification of total, soluble, and dialyzable metal fractions.

Main Results:

• White and very aged red Port wines exhibited lower Pb complexing affinity compared to other wines.
• Cu ligands in white wines were weaker but more concentrated than in other types.
• Pb complexing ligand concentrations (CC(inert)) increased post-digestion, while stability (K'(av)) decreased.
• Low dialyzable fractions for Pb (10-22%) and approximately 50% for Cu were observed during intestinal digestion.

Conclusions:

• Port wine type significantly influences Pb and Cu speciation and complexation.
• The bioavailable fraction of Pb is limited due to low intestinal dialyzability.
• Cu bioavailability is higher than Pb, with approximately half being potentially absorbable.