Moisture-responsive essential oil composite paper based on metal-organic framework for lily bulb preservation

The preservation of lily bulbs has attracted attention due to the reduction of shelf life caused by high humidity. In this study, a moisture-responsive carboxymethyl absorbent paper embedded with HKUST-1 (HKUST-1@CMAP) was successfully prepared by in-situ growth method. Characteristic peaks and crystallization peaks of HKUST-1 were observed in the FTIR spectra and XRD spectra of HKUST-1@CMAP, respectively. The loading capacity of clove essential oil (CEO) in composite paper was 4.62%. Essential oil composite paper (CEO-HKUST-1@CMAP) exhibited moisture-responsive release properties, with the release of clove essential oil increasing from 34.99% to 84.38% within 18 days as the moisture increased from 20% to 60%. Meanwhile, CEO-HKUST-1@CMAP showed excellent antimicrobial capacity, antioxidant property and biocompatibility. During storage, essential oil composite paper effectively delayed the browning of lily bulbs, maintained their firmness, and inhibited the growth of microorganisms, thereby maintaining the overall storage quality of lily bulbs stored at 25 °C for 16 days. In addition, CEO-HKUST-1@CMAP successfully improved cell membrane integrity by enhancing the activities of SOD and APX, inhibiting the activity of POD, and reducing the accumulation of MDA. In conclusion, CEO-HKUST-1@CMAP effectively prolonged the shelf life of lily bulbs, indicating that it is a promising preservative for the preservation of lily bulbs.