Fabrication and characterization of biobased electrospun pH indicators from black carrot anthocyanin-loaded polylactide

Biobased pH indicators were developed using nanofibrous mats which were produced from a solution of host polymer, polylactide, and anthocyanin from black carrot as a natural pH-sensitive colorant. Nanofibers having high surface area promoted the interaction of dye molecules with the ambient. Morphological, chemical, thermal, mechanical and wettability characterizations of the mats were conducted. The mats were treated with pH buffer solutions, the colorimetric sensing is visually detected, and measured by a spectrophotometer. When the nanofibrous mats, comprising 3 % (wv⁻¹) anthocyanin, were treated with buffer solutions, samples displayed a visible color change from reddish pink/dark purple to pinkish gray, and 50 % of them showed ΔE values, the total color difference, greater than 5, whereas 30 % of them showed ΔE values greater than 12. Therefore, the developed anthocyanin-loaded nanofibrous mats have a potential to be used in applications where the detection of pH change is critical, i.e. food packaging.