Compatibility of CNF with three polysaccharides having different surface charges and backbones (chitosan, methyl cellulose, and carboxymethyl cellulose) was investigated. Chitosan (CH) incorporation reduced water absorption (WA) of CNF films (P < 0.05). CH molecular weight (Mw) (68, 181, 287 kDa) and amount (10 and 20 g/100 g CNF in dry basis) impacted moisture barrier, mechanical, antibacterial, thermal, and structural properties of CNF films. Regardless of Mw, CH incorporation (20 g/100 g CNF) decreased (P < 0.05) WA of CNF films, and high Mw (287 kDa) CH (20 g/100 g CNF) incorporation resulted in lower film water solubility while increasing film water vapor permeability compared with low Mw CH (68 kDa) incorporation (P < 0.05). CNF film with low Mw CH (20 g/100 g CNF) exhibited antibacterial activity against L. innocua and E. coli. Interaction mechanisms between CH and CNF were investigated through thermal, structural, and morphology analyses using DSC, FTIR, and SEM, respectively. CNF films with low or high Mw CH incorporation (20 g/100 g CNF) were further validated as surface contact films for fresh beef patties, showing effectiveness to prevent moisture transfer between the layered patties. This study demonstrated the potential of using CNF-CH composite films as water resistant and antibacterial packaging for foods with high moisture surfaces.

Nowadays consumers are aware of environmental problems. As an alternative to petrochemical polymers for food packaging, researchers have been focused on biopolymeric materials as raw material. The aim of this study was to evaluate mechanical properties (toughness, burst strength and distance to burst), water adsorption, light-barrier properties and transparency of composite films based on cellulose, glycerol and polyvinyl alcohol. Scanning electron microscopy, spectral analysis (FT-IR and UV–VIS-NIR) and differential scanning calorimetry were performed to explain the morphology, structural and thermal properties of the films. Results showed that polyvinyl alcohol enhances the toughness of films up to 44.30 MJ/m3. However, toughness decreases when glycerol concentration is increased (from 23.41 to 10.55 MJ/m3). Water adsorption increased with increasing polyvinyl alcohol concentration up to 222%. Polyvinyl alcohol increased the film thickness. The films showed higher burst strength (up to 12014 g) than other biodegradable films. The films obtained have optimal values of transparency like those values of synthetic polymers. Glycerol produced a UV protective effect in the films, an important effect for food packaging to prevent lipid oxidative deterioration. Results showed that it is feasible to obtain cellulose-glycerol-polyvinyl alcohol composite films with improved properties.

Determination of selenium compounds in air, soil, water, and food samples is of interest as selenium's bioavailability and toxicity depend on its concentration level. Among analytical approaches, electrochemical sensors are more favorable due to their simplicity, time-saving, cost-effectiveness, and high sensitivity. In this study, we report electrochemical determination and analysis of selenium at the surface of a pencil graphite electrode modified with a sensing composite film composed of acetophenone (2,4-dinitrophenyl)hydrazone, polypyrrole, and copper nanoparticles. To produce durable films, cyclic voltammetry technique, as a facile modification procedure, was used. The electrochemical response of the fabricated modified electrode to selenium was evaluated using cyclic and square wave voltammetry techniques. The modified electrode presented excellent electrocatalytic ability with favorable electrochemical parameters (α = 0.24, log kₛ = 3.27 s⁻¹, and Γ = 3.74 × 10⁻⁷ mmol cm⁻²) for the reduction of selenium in acidic media with optimized pH of 2 and working potential of around −0.85 V (vs. SCE). The scanning electron microscopy images of the modified surfaces proved the formation of aggregates in nanoscale, indicating successful electrodeposition and electro-polymerization processes to modify the pencil graphite surface. This revealed a linear electrochemical response to selenium within the concentration range from 50 nM to 110 nM with the limit of detection (LOD) of 16.58 nM. The analytical application of the new sensor was also examined with respect to its applicability in food samples, such as milk, and water samples, including food wastewater samples, suggesting valid determination of selenium without any side interference.

Biopolymers of gellan gum (G), 2-hydroxyethyl cellulose (HEC), and lignin (L)-based binary and ternary sustainable composites were prepared for food packaging and biomedical application. The composite films were flexible and transparent or translucent with slight brown in color. The incorporation of lignin considerably improved the thermal and mechanical and hydrophobic properties of the composite films. The addition of 10 wt% of lignin to the composites increased the tensile strength by 54.3% and 59.2% respectively. The prepared lignin-based composite films showed high ultraviolet (UV) protection, with almost 100% protection against UVB (280–320 nm) and 90% against UVA (320–400 nm). The surface hydrophobicity of the composite films increased with the addition of lignin. The binary and ternary composites containing 1, 5, and 10 wt% lignin exhibited excellent radical scavenging activities. The gellan gum/HEC/lignin based composite films achieved the best biocompatibility. The obtained composites showed efficient antioxidant and non-cytotoxic activities, although there was no remarkable antimicrobial activity.