Design and fabrication of ethyl cellulose - chitosan-modified nanoparticles and evaluation of their efficiency for active food packaging

Abstract

Abstract: Extending the shelf life of food and avoiding food waste, as well as increasing concern for the environment, require the use of active and biodegradable packaging systems with multiple functions. Aim: The aim of this study is to produce biodegradable nanocomposite films based on hydrolyzed ethyl cellulose for active packaging using graphene oxide nanoparticles and chitosan to improve mechanical properties as well as antimicrobial and antioxidant properties. Materials and methods EC-based composite films were produced by solution casting, with the total solids content of the films set at 1.18% by weight. The EC powder (2 wt%) was hydrolyzed with a mixture of ethanol (70 %) and acetic acid (96 %) in a volume ratio of 30:70 at 65 °C for 1 h. For the preparation of the EC film with GO (EC-GO), the different GO concentrations were slowly added to the EC film and stirred for 1 h at 700 rpm and a temperature of 60 °C. The preparation of the EC film with CS was somewhat difficult because the combination of ethyl cellulose and chitosan forms a gel-like structure between hydroxyethyl cellulose and chitosanamine. It was therefore decided to first deactivate the functional amine groups of the chitosan by adding reducing agents such as Glc and GO or even a combination of both. CS-Glc and CS-Glc-GO solutions were therefore prepared according to the above explanations. Finally, the above solutions were slowly added to the EC solution and mixed at room temperature for 1 hour at 700 rpm and films were prepared, which were designated as EC+(CS-Glc), EC+(CS-GO) and EC+ (CS-Glc-GO). To avoid the presence of bubbles before casting, the films were degassed in an ultrasonic bath for 3 minutes. The optimal treatments were evaluated for mechanical properties, thickness measurement, solubility, moisture content, water vapor permeability, and antimicrobial and antioxidant properties. Results: Tensile strength (UTS) and elongation at break (EAB) (%) increased significantly with the inclusion of GO and/or Glu modified CS in composite films compared to EC alone and EC/GO film when the total film strength was kept constant. The SEM and AFM images show that the prepared films have acceptable coverage and uniformity. Chitosan and graphene oxide nanoparticles increased the solubility and permeability to water vapor. The highest antibacterial activity against Staphylococcus aureus and Escherichia coli was observed in composite films (EC-GO NPs) and (EC-CS/GO NPs), respectively. The release of the active compounds in terms of antioxidant and antimicrobial activity was controlled and slow, which is an important advantage due to the hydrophobic nature of the film. Conclusion: It appears that EC-based composite films with low dry mass and good antimicrobial and antioxidant properties can be considered as a cost-effective active film for food packaging. Keywords: Ethyl Cellulose, Graphene Oxide, Chitosan, Nanoparticles, Active Packaging