This study aimed to produce Plantago major seeds gum (PMSG) and carboxymethyl cellulose (CMC) antimicrobial nanocomposite film by adding Cerium oxide nanoparticles (CeO2 NPs) (2.5 and 5%W/W) as reinforcing additive and fenugreek seeds essential oil (FSEO) (4 and 8%W/W) as a bioactive agent. The nanocomposite films were prepared by casting method, and moisture content, moisture absorption, opacity, water vapor permeability (WVP), antimicrobial activity, and antioxidant properties of them were examined. FTIR, FESEM, XRD, and TGA tests were carried out to study the morphology, crystalline structure, and thermal stability of films, respectively. Moreover, mechanical properties, for instance, tensile strength (TS), elongation at break (EB), and thickness of the films, were measured. The results indicated that adding CeO2 NPs improved the mechanical properties and formed new crystalline structures on the nanocomposite films. The inclusion of 5% CeO2 NPs and 8% FSEO had a significant reduction in moisture content and moisture absorption (p\(<\)0.05). Besides, FSEO addition did not have a significant effect on the WVP amount (p\(>\)0.05). However, adding CeO2 NPs and FSEO caused a significant effect on antimicrobial and antioxidant properties, and the highest antimicrobial and antioxidant activities were obtained by the film containing 2.5% CeO2 NPs and 8% FSEO. The results showed that the TS was decreased by adding FSEO, and it increased by adding CeO2 NPs, especially at higher concentrations. EB was significantly affected by the addition of CeO2 NPs and FSEO, EB was enhanced by the addition of FSEO, and was reduced by the addition of CeO2 NPs. Instrumental analysis FTIR, FESEM, XRD, and TGA tests showed high potential of PMSG/CMC-based nanocomposite reinforced by CeO2 NPs and FSEO for food packaging technology.
