About one-third of the world's food is lost and wasted each year, along with excessive carbon emission, disposals, and other environmental issues. The rotting of perishable products like fruits and vegetables accounts for the largest percentage of food waste due to their short shelf life. The storage atmosphere (H2O, O2, CO2) acts as a key role in the preservation process and could regulate plants' physiological metabolism and microbial growth. In this work, a facile and biomimetic strategy is introduced for food preservation at room temperature employing PLLA (poly(l-lactic acid)) or chitosan porous microspheres as gas "switches" or "stomata" in a shellac membrane to regulate O2, CO2, and H2O permeability and CO2/O2 selectivity. Surface coatings on fruits or packaging films prepared through this strategy show exceptional preservation performance on five selected model fruits with different respiratory metabolisms. These hybrid materials could effectively control the gases (O2, CO2, and H2O) permeability and CO2/O2 selectivity by adding different amounts of porous microspheres or depositing small functional molecules, which demonstrate excellent antioxidant, antimicrobial, water-resistant, and reusable properties. This gas permeation control strategy has great potential in food preservation as well as other applications where a controlled atmosphere is required.
Keywords: biomimetics; controlled gas permeation; food preservation; hybrid membranes; microspheres.