Robust smartphone-assisted cellulosic smart label for real-time monitoring shrimp freshness under low temperature and high humidity conditions

Sustainable cellulosic fibers-based pH-sensitive smart labels have garnered attention in monitoring food freshness but face challenges under low temperature and high humidity due to poor wet strength and unreliable color response. To address this drawback, a “synergistic inner-outer action” strategy was proposed to construct cellulose/anionic polyacrylamide (APAM)/anthocyanin (Anth)/chitosan (CS) (CAAC) smart label. Negatively charged APAM, embedded in cellulose networks, acted as an “inner” host to bind “outer” positively charged CS via strong electrostatic interactions. The restricted polymer movement and densified nanostructures boosted the wet strength of CAAC₄ paper from 0.185 MPa to 12.795 MPa and reduced the Anth release from 70.89 % to 19.14 %. The CAAC₄ label showed high sensitivity to volatile ammonia, enabling real-time shrimp freshness monitoring through visible color changes. Integrated with a smartphone-based RGB analysis platform, the label allowed quick, visual color analysis. This approach not only enhanced the wet strength and color response of cellulose-based smart label, but also offered a reliable solution for intelligent packaging in harsh conditions.