Characterization of biocomposite films made from carboxymethyl cellulose, okra mucilage, and black cumin seed (Nigella sativa) oil by Response Surface Methodology

The primary aim of this study was to develop biocomposite films using carboxymethyl cellulose (CMC) (1 % w/v), okra mucilage (OM) (1–3 % w/v), and black cumin seed oil (BSO) (0–0.5 % v/v), based on the central composite design. The effects of OM and BSO concentrations on the properties of biocomposite films were evaluated using response surface methodology. Statistical analysis showed that all variables significantly contribute to the model (p < 0.05). The findings indicated that higher BSO concentrations considerably decreased (p < 0.05) the water vapor and oxygen permeability, moisture content, swelling factor, and water solubility of the produced films. Conversely, a rise in OM concentration notably increased (p < 0.05) the physical and barrier properties of the films. It was determined that an increase in OM concentration led to a decrease in tensile strength (TS), while the elongation at break (%EB) increased significantly (p < 0.05). Conversely, higher concentrations of BSO significantly improved both the TS and %EB values (p < 0.05). FE-SEM analysis revealed that for all films, microstructural irregularities increased with higher concentrations of OM and BSO. The formulation containing 1.82 % OM and 0.5 % BSO was identified as an optimal composition. FE-SEM and AFM analyses showed that the optimal film had higher microstructural discontinuity and surface roughness than the control film. The optimal film exhibited significantly higher antioxidant activity (p < 0.05) compared to the control film. Furthermore, FTIR analysis highlighted the presence of new intermolecular interactions within the functional groups of the optimal film’s matrix. Moreover, the optimal film demonstrated a higher melting temperature and a more amorphous structure than the control film. In conclusion, the optimized CMC/OM/BSO film presents promising potential for use in edible packaging. [Display omitted] •Developed new edible films using Carboxymethyl Cellulose (CMC), Okra Mucilage (OM), and Black Seed Oil (BSO).•Adding BSO improved the films’ barrier and mechanical properties.•Incorporating OM into the CMC-based film adversely impacted its barrier properties and tensile strength.•The properties of optimized and control films were scrutinized using SEM, AFM, FTIR, XRD, and DSC.