Triple-layer composite nanofiber pad with directional liquid absorption and controlled-release chlorine dioxide for postharvest preservation

Microbial infection, juice overflow, and water condensation from respiration and transpiration can cause premature spoilage of fresh produce. Here, a cellulose acetate/polyvinyl alcohol-g-polyacrylic acid/polyurethane (CA/PVA-g-PAA/PU) triple-layer nanofiber pad loaded with sodium chlorite and citric acid was prepared by electrospinning technique and thermal crosslinking, which possessed excellent liquid transfer, absorption, barrier, and antimicrobial properties. Depending on the wettability difference between the CA transfer layer and PVA-g-PAA absorbent layer, this pad could directionally transfer and absorb produce-generated liquid, preventing fresh produce from being wetted. Meanwhile, the PU barrier layer protected the paper packaging from being soaked. More importantly, absorbed liquid activated the reaction between sodium chlorite and citric acid for moisture-controlled releasing chlorine dioxide, thus inhibiting Escherichia coli, Staphylococcus aureus, and Aspergillus niger. In addition, the pad showed desirable biocompatibility, fresh-keeping effect, and sensory influence. Therefore, the antimicrobial absorbent pad with three functional layers provided an innovative strategy for designing multifunctional packaging.