Sustainable PLA biocomposite films incorporated with eucalyptus and wintergreen essential oils for stored grain protection: Structured performance relationships and dual antimicrobial–insecticidal functionalit

Post-harvest losses due to insect pests are a significant issue in stored grains. This study aimed to create biodegradable polylactic acid (PLA)-based packets embedded with essential oils and to assess their anti insecticidal activity in controlling the stored grain pest Sitophilus oryzae in sorghum under fumigation conditions. Essential oils from Eucalyptus and Wintergreen were included in PLA films at various concentrations (5%, 10%, 15%, 20%, and 30%). Fumigation tests were conducted by placing the packets with sorghum grains and test insects, and the mortality rates were recorded at 24, 48,72hr. Eucalyptus essential oil embedded packets shown 100% mortality in 48hrs , wintergreen essential oil embedded packets shown 100% mortality in higher concentration at 72 hrs. Analysis of the chemical compounds using Gas Chromatography-Mass Spectrometry indicated that eucalyptus oil had eucalyptol as the main compound, making up 51.14% of the peak area. In contrast, wintergreen oil was mainly made of methyl salicylate, constituting 64.58% of the peak area. The films were further examined for their physical and functional properties, such as mechanical properties of films, Fourier Transform Infrared Spectroscopy (FTIR), water vapor transmission rate (WVTR), antioxidant activity by using DPPH and ABTS method, antimicrobial activity, Differential Scanning Calorimetry (DSC), UV-visible spectroscopy, and Scanning Electron Microscopy (SEM). The results confirmed the successful inclusion of essential oils and the enhanced functional properties of the PLA films. In conclusion, this study indicates that essential oil-infused PLA-based biodegradable packaging may offer an effective, eco-friendly way to safeguard stored sorghum grains from insect infestation while also providing antioxidant and antimicrobial advantages.