Development of time-pH indicator nanofibers from natural pigments: An emerging processing technology to monitor the quality of foods

Colorimetric indicators produced from nanofibers have a high contact surface area, allowing better interaction of the indicator with the external environment. In this context, this study aimed to develop time-pH indicator nanofibers with natural pigments for use as an emerging technology in the control of food quality. The polymeric solutions were prepared with 13 percent (w v?1)polycaprolactone (PCL)and 6 percent (w v?1)poly (ethylene oxide)(PEO). The natural dyes added to the polymeric solution were curcumin and quercetin (2 percent, w v?1)with the addition of 0.5 or 1 percent (w v?1)of phycocyanin. Solutions with curcumin, quercetin, and phycocyanin only (2 percent w v?1)were also studied. The color change monitoring was performed for 24 h, followed up every 1 h, using buffer solutions (pH 2 to 7). The condition with 2 percent (w v?1)phycocyanin showed a color variation (?E ? 5)noticeable to the human eye in the pH range 3-6 in 5 h of analysis. Thus, the indicator developed with PCL/PEO nanofibers containing 2 percent (w v?1)of phycocyanin is a promising alternative in monitoring the quality of perishable foods, as it can visually estimate changes in pH over time.