Smart and bioactive packaging systems from anthocyanins and zinc oxide nanoparticles for quality monitoring and shelf-life extension of Nile perch (Lates niloticus)

Abstract

Anthocyanins possess high potentiality as natural pH-sensitive pigments, enableing their usages as safe alternatives for monitoring food quality. This study targeted the development of smart, active, and bioactive dipping solutions (SCS), comprising anthocyanin-rich extract from Hibiscus sabdariffa (HE) with green-synthesized zinc oxide nanoparticles (ZnONPs) stabilized in chitosan nanoparticles (ChNPs). The HE displayed distinct color transitions under different pH conditions, e.g. red to pink in acidic, violet in neutral, and green to yellow in alkaline media, signifying its potential as a freshness indicator. Green-synthesized ZnONPs exhibited smaller particle sizes (6.42-15.92 nm) compared to ZnONPs prepared without HE (26.92-41.24 nm). XRD confirmed ZnONP crystallinity, while UV-Vis absorption at 377 nm verified nanoparticle formation. Zeta potential values indicated stability, with ZnONPs (- 28.73 mV), and ChNPs (+ 36.4 mV). The SCS demonstrated strong antioxidant activity (89.29% DPPH scavenging) and antibacterial effects against Escherichia coli and Staphylococcus aureus. FTIR confirmed successful component interactions, and SEM analysis verified nanocomposite formation. Application of SCS on Nile perch fillets stored at 4 °C effectively delayed spoilage, extending shelf life by up to six days. Moreover, the color transition from red to green during storage provided a visual signal of quality decline. These findings highlight the potential of anthocyanin-based nanocomposite systems with ZnONPs and ChNPs and as eco-friendly smart packaging solutions for real-time fish quality monitoring and preservation.