CMC/cassava starch films containing black wolfberry anthocyanins and tea polyphenols: Physicochemical...

In this study, a novel intelligent colorimetric pH-indicating film was developed using carboxymethyl cellulose (CMC)/cassava starch (CS) as the matrix incorporated with black wolfberry anthocyanins (BWA) and tea polyphenols (TP), and its potential for cherry preservation and visual freshness indication was evaluated. The BWA-TP system formed a compact network through hydrogen bonds and π-π stacking interactions, which significantly enhanced the mechanical strength and barrier properties of the film. The combined interaction of BWA and TP improved the antioxidant capacity of the composite film (DPPH: 89.20%, ABTS: 92.38%) and its antibacterial activity against S. aureus and E. coli. Meanwhile, hemolysis test results indicated favorable hemocompatibility of the composite film. Owing to the pH-responsive structural transition of BWA, the film exhibited distinct color changes in the pH range of 2.0-12.0. This enabled visual pH colorimetric indication for intelligent freshness monitoring. Importantly, within 15 days of room-temperature storage, the composite film alleviated multiple deterioration indicators of cherries with a final weight loss rate of 14.17%, and distinct film color shifts (ΔE > 18) enabled visual tracking of fruit spoilage. In conclusion, this multifunctional film integrates active preservation and intelligent colorimetric sensing, exhibiting great potential as a high-performance intelligent packaging material for fruit and vegetable storage.