An intelligent aerogel composed of anthocyanins, natural fiber, carboxymethyl cellulose, and sodium alginate for monitoring fish freshness

Abstract

This study aimed to develop a natural colorimetric aerogel based on carboxymethyl cellulose (CMC), sodium alginate (SA), black goji anthocyanin (BGA), and various natural fibers such as cotton fiber (CF), silk fiber (SF), and down fiber (DF) via a combined approach of ionic gelation and freeze drying for monitoring fish freshness. Various colorimetric aerogels, (CMC/SA, CMC/SA/CF, CMC/SA/SF, and CMC/SA/DF) were developed and analyzed. Among them, CMC/SA aerogel showed higher density (0.054 g/cm³) with no surface pores, while CMC/SA/SF had a large surface area (18.6214 m²/g) with uniformly higher porosity (97.11 %) and a lower density (0.024 g/cm³). Moreover, the CMC/SA/SF aerogel exhibited greater mechanical properties and color sensitivity at various pH compared to other aerogels, which was then used as an indicator label for monitoring fish freshness during storage at 4 °C and 25 °C. The label aerogel became blue from purple, when the values of TVB-N, TVC, and pH reached 32.92 and 26.91 mg/100 g, 9.41 × 10⁷ and 8.7 × 10⁷ CFU/g, and 6.99 and 7.15 at 4 and 25 °C, respectively, exhibiting the level of fish deterioration. Taken together, the CMC/SA/SF colorimetric aerogel shows great potential for application as an intelligent package in monitoring the freshness of fish.

Keywords: Black goji extract; Carboxymethyl cellulose; Colorimetric aerogel; Monitoring fish freshness; Natural fibers; Sodium alginate.