Theoretical Prediction of the Color Expression of Malvidin 3-Glucoside by In Silico Tristimulus Colorimetry: Effects of Structure Conformational Changes and Molecular Interactions

The development of in silico methods for accurately predicting the perceived color of wine pigments is still a challenge for current theoretical approaches. In this work, computational tools (docking and molecular dynamics) in conjunction with TD-DFT calculations and the basis of tristimulus colorimetry in the CIELAB color space were applied to study the molecular mechanisms involved in the color expression of malvidin 3-glucoside. The 3D structure of different malvidin 3-glucoside conformers was obtained, and the theoretical visible spectra were computed, providing insight into the effects of the internal distortions of the flavylium chromophore (involving the dihedral angle) and non-covalent interactions (with a grape seed peptide) on the predicted color due to copigmentation phenomena. The results show a strong relationship between the conformational changes of the flavylium cation and the predicted CIELAB parameters, mainly the hue. The simulated malvidin 3-glucoside–grape seed peptide interactions allowed a good hue prediction of energetically favorable conformations of anthocyanin complexes as part of the comprehensive appearance in wines.