Development of active and intelligent pH food packaging composite films incorporated with litchi shell extract as an indicator

The anthocyanin-rich litchi shell extract (LE) was mixed with the matrix to prepare active/intelligent food packaging composite films. The microstructure and properties of composite films were characterized. The results showed that the composite films incorporated with LE had texture-oriented layered, compact, uniform cross-sections. The composite films with LE showed different degrees of red. The composite films had similar water vapor transmission rates (1.62-1.65 x 10(-12) g center dot cm/cm(2)center dot Pa center dot s). However, gelatin/chitosan/polyvinyl alcohol/ litchi shell extract (Gel/Csa/PVA/LE) film had better UV blocking rates (0-20 %), the best tensile strength (18.6 MPa) and elongation at break (116%). When the composite films monitored for fish freshness at 4 degrees C (10 d) and 25 degrees C (3 d), the Gel/Csa/PVA/LE film had the pH sensitivity to show an obvious color change at 25 degrees C, 1th day. The results suggested that the Gel/Csa/PVA/LE film could be applied to intelligent food packaging film to indicate the freshness of fish.

Automated summary

The incorporation of anthocyanin-rich litchi shell extract (LE) in composite films improved their microstructure and properties. The composite films showed texture-oriented layered, compact, and uniform cross-sections and exhibited different degrees of red due to the presence of LE. The Gel/Csa/PVA/LE film, in particular, demonstrated better UV blocking rates, tensile strength, and elongation at break, and was capable of indicating fish freshness through pH sensitivity.