Engineering a shellfish-inspired bio-based double-layered smart packaging material with enhanced water resistance and barrier performance for universally applicable meat freshness monitoring

In this work, inspired by the biological structure of shellfish, a bio-based bilayer smart packaging film was developed for real-time visual monitoring of meat freshness. Specifically, the bilayer smart packaging film consisted of a protective outer layer and a functional inner layer. The protective outer layer had a shell-like “brick and mortar” microstructure, consisting of a hard substance (mica powder) and a bio-based soft substance (polylactic acid), which provided the film with improved water resistance and gas barrier properties (WVP = 5.38–6.05 g·m⁻¹·s⁻¹·Pa⁻¹). The functional inner layer consisted of a composite polysaccharide matrix (guar gum, sodium alginate and carboxylated cellulose nanofibers) and three natural indicators (black rice extract, curcumin and their composite indicator), which provided the film with enhanced light barrier property (T₆₀₀: from 61.6 to 4.0 %), antioxidant capacity and pH-responsive property. Notably, this bilayer smart packaging film prepared by the shellfish bionic strategy demonstrated universal applicability of freshness monitoring for three typical meats (chicken, pork and shrimp). In brief, this work provides promising and feasible results based on an aquatic organism biomimetic strategy for the preparation of sustainable and high-performance bio-based smart packaging materials, which has potential applications in the field of food quality maintenance and food safety monitoring.