Novel konjac glucomannan films with oxidized chitin nanocrystals immobilized red cabbage anthocyanins for intelligent food packaging

An active and intelligent film was developed by immobilizing red cabbage anthocyanins (RCA) into an oxidized-chitin nanocrystals (O-ChNCs)/konjac glucomannan (KGM) matrix. O-ChNCs were selected as a host complex to anchor RCA and were considered as a reinforcement filler in the films. Zeta-potential, Fourier-transform infrared spectroscopy, X-ray diffraction, rheology, and release results revealed that RCA interacted with O-ChNCs through electrostatic interactions and altered the complex spatial structure between KGM and O-ChNCs. Microstructure observations showed that O-ChNCs and RCA were well distributed in a KGM matrix. Although the incorporation of RCA decreased the mechanical performance and light transmittance of the films, it endowed the KGM/O-ChNCs/RCA (KCR) films with an excellent UV-barrier, and antioxidant and antibacterial properties. The KCR films exhibited a good release control of RCA and a predominant Fickian diffusion release mechanism. Moreover, the KCR films were pH-sensitive and showed remarkable color changes in different buffer solutions. Therefore, KCR films have promising potential for applications in active and intelligent food packaging.