Multifunctional double-layer film incorporated Pickering emulsions and polyphenol-anthocyanin co-pigmentation for maintaining and monitoring shrimp freshness

To real-time monitoring and maintaining food freshness, a colorimetry-enhanced versatile double-layer intelligent packaging was developed. The two-layer structure was constructed using a layer-by-layer casting strategy. Specifically, anthocyanin (Ant) combined with varying contents of tannic acid (TA) to cross-linking highly stable co-pigments, which constructing acid/base responsive indicator inner layer (C/AT) with carrageenan matrix. Additionally, bacterial nanocellulose (BNC) was obtained via acid hydrolysis and combined with gelatin to form mixture (BNC/Gel), which were then used as a stabilizer for creating oregano essential oil Pickering emulsion (BGO). The BGO was subsequently integrated into konjac glucomannan matrix, which constructing high-barrier, bacteriostatic outer layer (K/BGO). The obtained K/BGO-C/AT films exhibited excellent antibacterial and antioxidant properties, along with a sensitive, reversible and rapid response to pH/NH₃. The bilayer film boasted exceptional barrier, mechanical properties, making it easily processable into primary packaging and smart labels of extended function. The double-layer K/BGO-C/AT_2.0 film showed minimal changes in ∆E and TVB-N (17.36 mg/100 g) even after 72 h during monitoring and maintaining the shrimp freshness, underscoring its potential to enhance food safety and extend shelf life.