Electrospun zein nanofibers containing <scp> <i>Beta vulgaris</i> </scp> betalains and Bromocresol purple dye as <scp>pH</scp> ‐sensitive colorants for monitoring fruit spoilage

Abstract In this study, Vitus vinifera coated with fabricated smart nanofibers such as zein (ZE), zein blended with betalains natural colorant (ZEBT) and zein blended with bromocresol purple dye (ZBCP) nanofibers. Betalains (BTs) natural colorant from Beta vulgaris was extracted using Soxhlet apparatus. The rheology studies showed that the BTs and BCP dye blended solution had a higher viscosity than the ZE solution. Optimisation studies were performed to obtain a smooth morphology of ZE, ZEBT and ZBCP nanofibers and were characterised using Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analyses. The ZEBT and ZBCP nanofibers could be employed with reversible shifts ranging from pH 1.0–13.0. The spoilage monitoring results on black grapes with ZEBT showed a significant color change indication through pH change than the other fibres. These new pH‐sensitive materials can be used as halochromic indicators for monitoring black grapes spoilage.