Optimized carboxymethyl cellulose and guanidinylated chitosan enriched with titanium oxide nanoparticles of improved UV-barrier properties for the active packaging of green bell pepper.

Edible films based on chitosan biguanidine hydrochloride and CMC were optimized for the minimum water vapor permeability (WVP) using the 3-level factorial design. Titanium oxide nanoparticles (nTiO) were incorporated in different contents into the optimized film (O). FTIR and H NMR confirmed the successful preparation of films. FE-SEM showed that nTiO was homogeneously distributed, with a size of about 25.78 nm for the film containing 5 wt% of nTiO. XRD was used to study the film's crystallinity, and calculate the crystallite size of nTiO using Debye-Scherrer Equation. Thermal stability, by TGA, was improved while the water vapor permeability was reduced upon increasing the nTiO content. Color measurements showed that the nTiO incorporation didn't significantly affect the transparency. Elongation at break was decreased upon nTiO incorporation while tensile strength and Young's modulus were increased with increasing nTiO up to 3 wt% then begin to decrease. The nanocomposites exhibited significant UV-barrier properties and enhanced antimicrobial activity especially at high contents of nTiO. Shelf-life studies on green bell pepper coated with the nanocomposite films showed excellent resistance to mass loss and spoilage during storage. The obtained data confirm the efficiency of the prepared nTiO nanocomposite films to extend the shelf-life of food.