## 4 Conclusions  
The combination of quantum calculations and subsequent spectral analysis through tristimulus colorimetry in the CIELAB color space has allowed for an accurate prediction of the color modulation of mv3 glc in its flavylium cation form, related to torsions in the chromophore and non-covalent interactions. It was confirmed that the PCM-TD-DFT calculations based on the B3 LYP/6-31+G(d,p) theoretical level reflect the strong structure-color relationship of anthocyanin pigments by means of the prediction of quantitative and qualitative color variations considered visually perceptible and dependent on the \(\theta\) torsion. Colorimetric changes (red-orange or bluish effects) in mv3 glc due to non-covalent interactions (\(\pi\)-alkyl and \(\pi\)-\(\pi\)) with a grape seed peptide have also been predicted by using the theoretical methodologies described above, which could support experimental observations. Nevertheless, from a technological standpoint, future research should aim to supplement the findings with experimental data and cross-validate them with alternative theoretical approaches to significantly enhance the reliability and robustness of the predictions, ensuring that conclusions drawn from molecular modeling are validated. It is essential to improve the integration of each functional to comprehensively address the spectral and structural properties, optimizing the strengths already established by the method used and complementing them with the capabilities of other functionals.  
**Supplementary Materials:** The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/app15084238/s1](https://www.mdpi.com/article/10.3390/app15084238/s1)]([https://www.mdpi.com/article/10.3390/app15084238/s1](https://www.mdpi.com/article/10.3390/app15084238/s1)): Figure S1: Nine different conformations of the interaction between mv3 gcl and the grape seed peptide (R.ADVVTPPR.G) obtained by docking studies; Figure S2: Theoretical visible absorption spectra of the mv3 gcl-GSP complexes (docking conformations 1, 3, 5, and 7) calculated with the dispersion-corrected hybrid functional B3 LYP.  
**Author Contributions:** Conceptualization: [PERSON]; methodology: F.C.-G.; investigation: F.C.-G.; data curation: F.C.-G.; writing--original draft preparation: F.C.-G.; writing--review and editing: [PERSON]-[PERSON], [PERSON], [PERSON] and [PERSON]; validation: [PERSON] and [PERSON]; image design: [PERSON]; supervision: [PERSON]; project administration: [PERSON] and [PERSON]; funding acquisition: [PERSON] and [PERSON]-[PERSON]. All authors have read and agreed to the published version of the manuscript.  
This research was financially supported by Project PID2021-127126 OB-C22 funded by MICIU/AEI/10.13039/501100011033 and FEDER, UE. Consejeria de Universidad, Investigacion e Innovacion de la Junta de Andalucia, Spain (Project PAIDI2021 PROYEXCEL_00578). F.C.G acknowledges the PhD grant PRE2018-087184 funded by ESF Investing in your future. M.F.L.M acknowledges the PhD grant PRE2022-104543 funded by MICIU/AEI/10.13039/501100011033 and by \"ESF+\".  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
Authors thank the assistance of the Biology Service (SGI, Universidad de Sevilla, Spain) and the Scientific Computation Center of Andalusia (CICA) for the computing services they provided.  
The authors declare no conflicts of interest.