Investigation of the structural and physical properties, antioxidant and antimicrobial activity of konjac glucomannan/cellulose nanocrystal bionanocomposite films incorporated with phlorotannin from Sargassum.

In this study, environmentally friendly bionanocomposite films were prepared by incorporating phlorotannins from Sargassum (PS) into konjac glucomannan (KGM)/cotton cellulose nanocrystals (CNC) composites. The effects of different concentrations of PS (5%, 9%, 13%, and 17%, w/w) on the microstructure, physical properties, antioxidant and antibacterial activities of the resultant bionanocomposite films were evaluated. The results of scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectra showed that PS was well compatible with the KGM/CNC composites matrix, which led to form a compact and uniform structure of the films. Thermogravimetric analysis and differential scanning calorimetry demonstrated that incorporating PS improved the heat stability of KGM/CNC bionanocomposite films. And addition of the appropriate amount of PS improved the mechanical and water-vapor barrier-related properties of the bionanocomposite film. For instance, with 9% PS, the tensile strength of the KGM/CNC/PS bionanocomposite film increased by 33.9%, and the water-vapor transmittance decreased by 41.67% compared to that of the KGM/CNC films. Moreover, the addition of PS endowed the KGM/CNC film with excellent antioxidant and antibacterial properties. Therefore, KGM/CNC/PS bionanocomposite films have great potential to be applicated as active packaging in the food packaging industry.

Development and characterization of electrospun nanofibers based on pullulan/chitin nanofibers containing curcumin and anthocyanins for active-intelligent food packaging.

An electrospun nanofiber based on pullulan/chitin nanofibers (PCN) containing curcumin (CR) and anthocyanins (ATH) was developed using an electrospinning technique for active-intelligent food packaging. The results of scanning electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy indicated that CR and ATH were successfully immobilized on the film-forming substrate based on PCN. The physical and chemical properties of nanofibers with no colorant, a single colorant, and double colorants were compared. The nanofiber containing ATH and CR (PCN/CR/ATH) had stronger antioxidant and antimicrobial activities than those of nanofibers containing CR (PCN/CR) or ATH (PCN/ATH). With respect to pH sensitivity, the color of the PCN/CR nanofibers did not change obviously, but the color of the PCN/ATH and PCN/CR/ATH nanofibers changed significantly with the change in pH. Furthermore, the PCN/CR/ATH nanofibers clearly changed color with the progressive spoilage of Plectorhynchus cinctus at room temperature. Therefore, the electrospun PCN/CR/ATH nanofiber have great application potential in active-intelligent food packaging.

Effect of carboxylation cellulose nanocrystal and grape peel extracts on the physical, mechanical and antioxidant properties of konjac glucomannan films.

Active bionanocomposite films were prepared by incorporating konjac glucomannan (KGM) as a matrix, with carboxylation cellulose nanocrystal (C-CNC) as a reinforcement agent and grape peel extracts (GPE) as a natural antioxidation agent. The effects of C-CNC and/or GPE addition on the structural, morphological, barrier, thermal, mechanical and antioxidant properties of the bionanocomposite films were investigated. The rheological results of film forming solutions revealed that C-CNC and GPE were well dispersed in the KGM matrix. Scanning electron micrographs observed the addition of C-CNC had little effect on the microstructure, while more roughness and unevenness were observed on the film surface and cross-section with the C-CNC and GPE. Furthermore, the water vapor barrier property and transparency of the films improved by the addition of the C-CNC and GPE. Notably, the incorporating of C-CNC or GPE significantly alter the mechanical of the KGM/C-CNC/GPE bionanocomposite films. The highest tensile strength was achieved for the KGM/GPE bionanocomposite film with 10 wt% C-CNC, indicating C-CNC and GPE had synergistic effect on enhancing the TS of KGM film. Moreover, the KGM/C-CNC/GPE films exhibited strong antioxidant activity. These results suggested that KGM/C-CNC/GPE bionanocomposite films can be used as an active food packaging for increasing shelf life of packaged foods.