Curcumin@γ-CD-MOFs reinforced regenerated cellulose films: A sustainable platform with antibacterial-antioxidant-UV shielding triad for fruit packaging and freshness monitoring.

Intelligent indicator films for food spoilage detection have emerged as an effective strategy to mitigate foodborne diseases and reduce food waste in modern life. However, large-scale fabrication of such intelligent films with integrated biosafety, biodegradability, and multifunctionality remains a significant challenge. Herein, a facile and feasible gel immersion technique was developed to prepare biodegradable cellulose/curcumin indicators with good antibacterial, antioxidant, and anti-ultraviolet properties by employing γ-CD-MOFs as curcumin carriers. The structure and performance of the cellulose/curcumin@γ-CD-MOFs films were found to be highly dependent on curcumin@γ-CD-MOFs concentration. Although the tensile strength of cellulose/curcumin@γ-CD-MOFs film decreased with increasing curcumin@γ-CD-MOFs content, the tensile strength of Film C-Cur5 (highest loading) still reached 94.26 MPa, maintaining good mechanical properties. Notably, the integration of curcumin@γ-CD-MOFs substantially enhanced the anti-ultraviolet, antioxidant, and antibacterial capacities of the cellulose composites. Specifically, the average transmittance of cellulose composites in UVA, UVB, and UVC regions was reduced from 86.15%, 80.24%, and 56.75% to 3.55%, 5.40%, and 3.18% for Film C-Cur5, respectively. Simultaneously, the radical scavenging rate of composite films reached a maximum of 95.90%. Meanwhile, the color of the composite films was strongly impacted by both curcumin concentration and pH value, and Film C-Cur5 exhibited the highest sensitivity to pH changes. Furthermore, the biosafe and biodegradable cellulose/curcumin@γ-CD-MOFs films were further applied to the real-time monitoring of strawberries and apricots freshness and packaging of fresh-cut apple. In conclusion, the pH-sensitive and biodegradable cellulose/curcumin@γ-CD-MOFs composite films with enhanced performance were successfully developed, demonstrating great potential for applications in fruit packaging and freshness detection.