Natural dye from Clitoria ternatea and its halochromic behavior

Clitoria ternatea anthocyanin extract is a promising natural colorant for halochromic applications; however, its practical use depends on stability under realistic relevant processing and environmental conditions. This study systematically evaluated aqueous Clitoria ternatea extract through UV–Vis spectroscopy, LC-DAD-MS analysis, degradation kinetics, reagent compatibility and textile dyeing trials. The extract exhibited well-defined pH-dependent spectral transitions across pH 1–12, with absorption maxima shifting from ~ 549–553 nm under strongly acidic conditions to ~ 619–626 nm under near-neutral to moderately alkaline conditions. LC-DAD-MS confirmed a multicomponent anthocyanin profile consistent with ternatin-related pigments. Stability studies showed apparent first-order degradation with excellent stability at 4 °C (half-life 31–36 days) than at elevated temperatures, particularly at 80 °C, while light/dark effects were wavelength-dependent and not fully explained by the presented data. Chemical compatibility tests revealed that common electrolyte systems such as Na2SO4 largely preserved the chromophoric structure, while transition metal ions (Fe2+ and Cu2+) induced spectral changes associated with complexation and oxidation, and Na2SO3 caused rapid bleaching. Dyeing trials on multifiber fabrics demonstrated preferential dye uptake by cellulose-based fibers, particularly cotton, which exhibited clear pH-responsive color changes (ΔE up to 33.55 after dyeing and 23.84 following acid treatment) while retaining the halochromic behavior observed in solution. Overall, Clitoria ternatea extract shows strong potential as a natural halochromic dye for textile-based sensing applications, however; dye fixation, durability, and long-term stability require future improvement.