PBAT/TPS-based intelligent films loaded with anthocyanin microcapsules for monitoring shrimp freshness

To enable real-time indication of food freshness and safety, a pH-responsive, color-changing food packaging film was developed. Blueberry anthocyanin (BA) was encapsulated with polyethylene oxide (PEO) using microencapsulation technology to produce Blueberry anthocyanin - polyethylene oxide microcapsules (BA-PEO). These microcapsules were then incorporated into a poly(butylene adipate-co-terephthalate) (PBAT)/thermoplastic starch (TPS) matrix to fabricate a biodegradable film capable of in situ monitoring of food freshness. Appropriate addition of BA-PEO enhanced the thermal stability and tensile strength of the PBAT/TPS films. At a BA-PEO content of 2 phr, the oxygen permeability coefficient reached a minimum value of 1.47 × 10⁻¹⁵ cm³·cm·cm⁻²·s⁻¹·Pa⁻¹, representing a 20.3% reduction. However, the incorporation of BA-PEO increased both the water vapor transmission rate (WVTR) and water vapor permeability (WVP). At 4 phr BA-PEO, the WVTR and WVP were 115.20 g·(m²·24 h)⁻¹ and 2.23 × 10⁻¹⁴ g·(cm²·s·Pa)⁻¹, respectively. A ΔE*ab value greater than 5 indicates that the color change is directly observable. Therefore, the potential of PBAT/TPS films filled with BA-PEO microcapsules is demonstrated in the field of intelligent food packaging materials.