Development and characterization of soluble soybean polysaccharide/pullulan blend films enriched with essential oils

Soluble soybean polysaccharide (SSPS)/pullulan (PUL) blend films enriched with lavender essential oil (LEO) or clove essential oil (CEO) were prepared using the solution casting method. The structural, optical, mechanical, barrier, thermal, antioxidant, and antibacterial properties of the SSPS/PUL/LEO and SSPS/PUL/CEO films were investigated and compared. Scanning electron microscopy micrographs revealed randomly distributed micropores within the SSPS/PUL matrix after enrichment with essential oils (EOs). The addition of EOs significantly improved the UV-blocking performance, elongation at break (EAB), water resistance, antioxidant activity and hydrophobicity of the films. The results showed that the SSPS/PUL/CEO films exhibited nearly 100 % UV-blocking efficiency in the wavelength range of 190-290 nm, while achieving a maximum EAB of 90.6 ± 5.3 %. However, the tensile strength of the films decreased from 10.8 MPa to 5.6 MPa or 4.8 MPa upon the addition of 15 % LEO or CEO, respectively. Thermogravimetric analysis indicated that the addition of EOs had little effect on the thermal properties of the SSPS/PUL films. Both SSPS/PUL/LEO and SSPS/PUL/CEO films exhibited good antioxidant and antibacterial properties, with the SSPS/PUL/CEO film showing superior performance in both aspects. The results preliminarily suggest that the SSPS/PUL/EOs films have great potential to be used as active food packaging materials.