Development of a colorimetric pH indicator using nanofibers containing Spirulina sp. LEB 18

A colorimetric pH indicator was developed using nanofibers of poly(lactic acid) (PLA) and polyethylene oxide (PEO) combined with biomass of the microalga Spirulina sp. LEB 18. This study evaluates the potential use of microalgal biomass encapsulated in polymer nanofibers to develop a colorimetric pH indicator. Nanofibers containing the biomass were exposed to solutions with different pH values (pH 1-10), and color variations were measured using a colorimeter. The wettability analysis of the nanofibers showed hydrophilicity (zero angle with water), which allows ions to interact with the biomass, indicating a fast color response as a function of pH. When subjected to pH variations, indicators containing 1, 2 or 3% (w v^-1) of biomass provided ΔΕ values >12, indicating an absolute difference in color. Therefore, this innovative material has the potential to be applied as a intelligent indicator to verify food quality through a visual signal of the product condition.