Development of pH indicator from PLA/PEO ultrafine fibers containing pigment of microalgae origin

Phycocyanin is a pigment of intense blue color, constituting the biomass of microalga such as Spirulina. This pigment is sensitive to pH and this instability results in color change. Thus, phycocyanin fading may become interesting for application in intelligent packaging. The objective of the study was to develop PLA/PEO ultrafine fibers containing phycocyanin to be used as pH indicators membranes for food packaging. The ultrafine fibers were formed by electrospinning process. The average diameter of 1318 nm was obtained for PLA/PEO ultrafine fibers with 2% (w·v−1) of phycocyanin and 921 nm for those developed with 3% (w·v−1) of the dye. PLA/PEO ultrafine fibers with 3% (w·v−1) of the phycocyanin presented the best responses regarding the perception of color change (ΔE). With the highest thickness (68.7 μm) of the ultrafine fibers developed from 3% (w·v−1) of phycocyanin, the ΔE value found was 18.85 to the variation of pH 3 to 4 and for variation from pH 5 to 6 the value of ΔE was 18.66. Thus, the use of PLA/PEO ultrafine fibers containing phycocyanin as pH indicator is an innovative application for intelligent packaging, since the color of pigment changes depending on pH variation.