Carbon dots embedded carrageenan based compostable functional packaging films with barrier bio-coating for prawns freshness monitoring

Abstract

Biopolymer based intelligent packaging films with barrier properties are gaining significant attention in the food industry due to the compostability, food freshness monitoring potential and shelf life increment capability. In this work, ∼10 nm sized urea- dithiosalicilic acid based carbon dots (UCDs) with aggregation-induced emission (AIE) property are prepared and incorporated into carrageenan biopolymer to develop amine sensing packaging material. Composite film is coated with zein-stearic acid (Z/SA) mixture to improve the water barrier property with water vapour transmission rate value ≤40 g/(m2.day). The coated composite film (CAR3UCD-C) exhibited ammonia sensing capability with a limit of detection (LOD) of 0.6 μM and showed good free radical scavenging activity (70 % against ABTS radicals), high UV blocking property (∼92 % reduction) as well as antibacterial activity against E. coli and S. aureus. The developed films showed better tensile strength (>50 MPa) and good thermal stability (till 200 °C). The material effectively distinguished the freshness states of prawns through fluorescent color change from orange to blue upon spoilage. The coated film is completely degradable in soil within 35 days under ambient conditions. This film can be utilised as a promising intelligent barrier packaging material for monitoring real-time freshness of prawns and other protein-rich foods.