Development and characterisation of starch/alginate active films incorporated with lemongrass essential oil (Cymbopogon citratus)†

The development of active films based on biopolymers containing antimicrobial and antioxidant compounds has contributed to the improvement of food safety. In the present study, the composition of lemongrass (Cymbopogon citratus) essential oil (LEO) was evaluted by gas chromatography-mass spectrometry (GC-MS) analysis and the minimum inhibitory concentration (MIC) against S. aureus and E. coli bacteria was determined. Films based on cassava starch and sodium alginate were prepared incorporating different concentrations (0.0, 0.5, 1.0, and 1.5%) of lemongrass essential oil (FLEO). Their physicochemical, mechanical, optical, retention and release properties, as well as their antibacterial and antioxidant activities were evaluated. GC/MS analysis of lemongrass essential oil (LEO) revealed the presence of citral (39.12%) and citronellol (34.47%) as major components. A minimum inhibitory concentration (MIC) of 25 μg mL⁻¹ was observed for LEO against S. aureus and E. coli bacteria. A significant decrease (12.42%) in water vapour permeability (WVP), moisture content (12.68%) and solubility (18.47%) was found as the LEO concentration in the films increased. Scanning electron microscopy (SEM) analyses showed a uniform distribution of LEO in the films, while FTIR spectra revealed interactions between the components. X-ray diffraction (XRD) patterns indicated that the incorporation of LEO did not affect the structural stability of the films, showing a decrease in crystallinity of 8.4%. Furthermore, The results showed an antioxidant activity of 32.4%, bacteriostatic activity against S. aureus and E. coli and a more stable release and retention of essential oil (EO) in films containing 1.5% LEO. These results suggest that the developed films have potential for application in active packaging.