Multifunctional biopolymer films with tamarind carbon dots for fruit packaging with antimicrobial, UV barrier, and antioxidant properties

Background Carbon dots (CDs) sourced from tamarind (TCDs) represent a green approach to improve food packaging performance. Embedding these CDs into a biodegradable polymer system enhances the mechanical strength, optical characteristics, and antimicrobial activity, serving as a sustainable replacement for conventional plastics. Methods A multifunctional packaging film was fabricated by blending chitosan, polyvinyl alcohol (PVA), and starch. CDs, synthesized from Malabar tamarind fruit via a hydrothermal method, were then incorporated. The resulting mixture was cast into glass petri dishes and processed using solution casting technique to form uniform films. Significant findings The incorporation of well-dispersed TCDs into the polymer film, slightly reduced its transparency but significantly enhanced antioxidant activity, tensile strength, UV-blocking capability, antibacterial effects against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ). A preservation test assessed titratable acidity (TA %), weight loss, and appearance changes in packaged fruits. Grapes wrapped with 0.50 % TCD-infused polymer films retained higher TA %, lower weight loss, and a fresher appearance for 9 days. Similar results were observed for sliced tomatoes, by preventing shrinkage, overripening, and maintained freshness for 5 days. These findings confirm the potential of the fabricated composite films as a viable and efficient solution for food wrapping applications.