Abstract Flexible films based on bacterial cellulose (BC) and polyaniline (PAni) were developed as potential colorimetric indicators of fish freshness in smart packaging. This comparative study examines the in situ synthesis of PAni on BC substrates produced using the Hestrin-Schramm medium and a novel alternative (saline) culture medium. The structural characteristics, electrical properties, and sensitivity to ammonia vapor of the films were evaluated at different polymerization times. Films obtained with a shorter polymerization time (5 min) exhibited, after doping, higher conductivity, with values of 6.35 × 10⁻ 4 and 9.70 × 10⁻ 4 S cm⁻ 1 for those produced in Hestrin-Schramm and Saline media, respectively. Doping and dedoping cycles demonstrated good reversibility in both the optical and electrical properties of the films, an essential feature for reusable sensors. The BC-PAni films were further evaluated as sensors for ammonia vapor, released during fish degradation under ambient conditions. The color variation of the films was observed over a period of 6 days, changing from green (corresponding to the emeraldine salt form of PAni) to blue (emeraldine base), as the fish deteriorated. These results indicate that BC-PAni films are promising for low-cost colorimetric labels to monitor fish freshness in smart packaging.
Santos et al. (Mon,) studied this question.