Effect of cellulose nanocrystals and green synthesized silver nanoparticles on mechanical properties and antimicrobial activity of banana flour/agar composite films.

This study characterized the physicochemical and functional properties of nanocomposite films synthesized by incorporating cotton linter cellulose nanocrystals (CN) and green silver nanoparticles (AgNPs) into banana flour/agar. The results showed that CN could not enhance the tensile strength of the B/A nanocomposite films, but it did prolong the antibacterial activity against the Gram-positive bacterium Listeria monocytogenes when combined with AgNPs. However, the binary blend of CN and AgNPs resulted in a flocculated morphology on the film surface, causing an increase in the film brittleness and a decrease in the water solubility, elongation, and final decomposition temperature. Unfortunately, none of the nanocomposite films were found to inhibit the growth of the Gram-negative species Escherichia coli within 12 h. Further research is needed to assess the migration release of CN/AgNPs in nanocomposite films and to determine their potential for use as active food packaging.

Development and characterization of banana flour film incorporated with montmorillonite and banana starch nanoparticles.

Banana flour film is an alternative biopolymer material but still needs improvement of its mechanical properties and water vapor permeability. Banana starch nanoparticles (BSNs), prepared using miniemulsion cross-linking, make an interesting reinforcing agent. The properties of plasticized banana flour film (PBF) were characterized incorporated with 5% (w/w) of either montmorillonite; MMT-Na+ (PBF-M) or BSN (PBF-B), including a mixture of nanoparticles at 1:1 for 5% (PBF-MB5) and 10% (PBF-MB10). PBF-MB5 provided better improvement in the film mechanical and water barrier properties compared with PBF-B. Moreover, PBF-MB5 exhibited an intercalated structure as confirmed by the shift peak of pristine MMT-Na+ from 2θ=7.3 to 3.9° and the increase in the d-spacing from 1.21 to 2.26nm in X-ray diffraction. Fourier transform-infrared spectra confirmed the intercalated structure. Therefore, the mixture of BSN and nanoclay at 5% was sufficient to reinforce the biopolymer films as a biomaterial packaging for food and pharmaceutical applications.

One-step preparation of banana powder/silver nanoparticles composite films.

Silver nanoparticles (Ag-NPs) were synthesized using banana powder as a reducing and stabilizing agent, and banana/Ag-NPs composite films with different concentration of Ag-NPs were prepared simultaneously. The composite films were yellowish brown and exhibited characteristic plasmon resonance peak of Ag-NPs at 430 nm. The optical, mechanical, water vapor barrier, thermal stability, and antimicrobial properties of the composite films were greatly influenced by the concentration of Ag-NPs. The composite film with a silver concentration of 1.0 mM demonstrated the highest tensile strength, thermal stability, transparency, and water contact angle with the lowest water vapor permeability (1.36 ± 0.10 × 10-9 g m/m2 Pa s). Also, the composite films incorporated with 1.0 mM of Ag-NPs exhibited a strong antibacterial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) food-borne pathogenic bacteria.