Pigment Analysis in Red and Rosé Wines by Tristimulus Colorimetry

The pigment composition of red and rosé wines was determined by tristimulus colorimetry using the thin-layer transreflectometric technique at two pH levels. The magnitude of change on acidification in chromaticity coordinates, expressed as (Δr² + Δg²)^1/2, and in blue transreflectance, expressed as Δ-log B, provide quantitative measures of pH-responsive anthocyanin pigment. The Δ-log B readings can be interpreted in terms of the contribution to total absorption by the pH-responsive and pH-non-responsive absorbing components.