Mechanical Properties and Antioxidant Activity of Sweet Potato Starch Film Incorporated with Lemongrass Oil

This study was carried out to investigate the mechanical properties and antioxidant activity of starch based film containing essential oil. Active antioxidant films have been prepared with sweet potato starch by incorporating lemongrass oil. Sorbitol with different concentration levels (10-50% w/w dry starch basis) has been used as a plasticiser. The process begins with the extraction of sweet potato starch into powder, followed by the process of gelatinisation of starch, mixing the solution with plasticiser and incorporation of lemongrass oil before casting. Analysis on the mechanical properties using a universal testing machine and antioxidant activity using 2, 2-diphenyl -1-picrylhydrazyl (DPPH) assay were carried out. The film with thickness of 0.1±0.01 mm showed tensile strength (TS) and elongation at break at (EAB) 69.22-307.16 MPa and 5.39-57.72% respectively. The increasing concentration of lemongrass oil resulted in a significant increase in EAB but reduction in TS. The antioxidant activity of the lemongrass oil in starch-based film was 29-43% and increased with the increase of lemongrass oil concentration. Thus, the incorporation of essential oil in the starch based film was found to be directly affected by the mechanical properties and the antioxidant activity related to the stability, shelf life and application of the film on the packaging area.