Aerogel colorimetric label sensors based on carboxymethyl cellulose/sodium alginate with black goji anthocyanin for monitoring fish freshness

A novel colorimetric aerogel was developed by the complexation of carboxymethyl cellulose (CMC), sodium alginate (SA), and black goji anthocyanin (BGA) followed by freeze-drying for monitoring fish (Coho salmon) freshness during storage at 4 °C and 25 °C. The various aerogels (C/S/B3:1, C/S/B2:1, C/S/B1:1, C/S/B1:2, and C/S/B1:3) externally and internally were characterized using SEM, FTIR, XRD, DSC, and TGA. Among them, the aerogel composite C/S/B1:2 exhibited the most uniform pore size, largest specific surface area, rapid color changes in various alkaline vapors (5 μM and 50 μM), and better mechanical strength. Furthermore, the colorimetric aerogel became dark blue from light purple during fish storage at temperatures of 4 °C and 25 °C when it reached pH 7.49 and 7.33, TVC 8.9 × 10