Development and Characterization of Rice Starch–Lemon Essential Oil Nano-emulsion-Based Biodegradable Films for Active Food Packaging

The current crisis of plastic pollution urges the development of high-performance and biodegradable packaging alternatives. This brings into focus the use of biopolymers like rice starch for the development of active food packaging. Accordingly, this study aimed at the development and characterization of rice starch films incorporated with lemon essential oil using nanoemulsion technology and comparing their performances with those of bulk emulsion and control films. The LEO nanoemulsion had a significantly smaller mean particle size (87.3 ± 56 nm) and a higher colloidal stability, as depicted by a high zeta potential (-62.8 mV) and low polydispersity index of 0.24, than the bulk emulsion, which had particle sizes in the range of 4251.2 ± 1297 nm. The nanoemulsion-based films in this study, RS+LEONE, depicted enhanced physical properties comprising improved mechanical strength of about 16.8 ± 1.1 MPa and better transparency of about 76.8 ± 2.5% transmittance, and also enhanced water resistance, depicted by a lower moisture content and lower solubility of 9.0 ± 0.7% and 21.1 ± 2.0%, respectively. As such, RS+LEONE film also illustrated better functional efficacy, showing higher antioxidant activity of 99.03 ± 0.94% and higher antimicrobial activity against both Escherichia coli and Staphylococcus aureus with 11.0 ± 0.7 and 13.0 ± 0.8 mm, respectively. In general, the nanoemulsion film outperformed its bulk emulsion and control film counterparts for all the evaluated parameters. The rice starch-LEO nanoemulsion film developed herein, therefore, remains highly promising and functional for active biodegradable food packaging applications.