The antimicrobial synergy of polymer based nanofiber mats reinforced with antioxidants intercalated layered double hydroxides as a potential active packaging material

Perishable food post-harvest loss is a major global concern, and research is currently concentrated on creating active packaging materials. This research is focused in multiple antioxidants intercalated Layered Double Hydroxides (LDH) that are combined in one matrix, and their overall effect that defines as synergism, which successfully preserves perishable food by releasing antioxidants slowly. For this purpose, a hybrid LDH material of ascorbic-LDH, salicylic-LDH, and citric-LDH was synthesized, characterized and incorporate into electrospun nanofiber mat to be used as a potential active packaging material. Antioxidants intercalated Mg/Al LDH was synthesized and successfully characterized by PXRD, FTIR, XPS, Raman, SEM and EDS. The shifts in the LDHs' peaks in PXRD indicated the successful incorporation of antioxidants into LDH. FTIR, Raman and XPS data clearly indicated the establishment of metal-oxygen bonds by observing the characteristic peaks. Morphological features and layered structure were clearly observed by SEM images. Antioxidants were slowly released from LDHs, and it was evaluated for time intervals up to 24 hrs. The hybrid LDH material exhibited the highest antioxidant activity with an IC50 value of 132.5µg/mL, where 234.1, 354.5, and 402.2µg/mL were reported for ascorbic-LDH, salicylic-LDH, and citric-LDH respectively. The hybrid LDH material incorporated electrospun mats showed the best antibacterial activity against the tested bacteria and clearly evidenced the synergistic activity of the combination of the nanohybrids. It has showed a minimal bacterial growth compared to other control samples (∼2.41 log CFU/mL). The shelf life of cherry tomatoes was studied at different physiochemical parameters with and without hybrid LDH material incorporated electrospun mats. The mat showed an extended shelf life of 42 days for cherry tomatoes, whereas the control sample showed a shelf life of 17 days. It is concluded that hybrid LDH material exhibited synergistic performance and the best antioxidant activity when comparing with mono LDH materials.