Multifunctional PVA composite pads enabled by carvacrol-loaded ZIF-8@PAN microspheres: sustained carvacrol release and long-term blueberry preservation.

To achieve long-term sustained release of active antibacterial substances and prolong food shelf life, polyacrylonitrile microspheres (PANAM) loaded with ZIF-8 and carvacrol (CV) were fabricated and then blended with crosslinked PVA matrix to prepare a composite pad (PANAM@ZIF-8@CV/PVA). SEM, XPS and XRD results showed ZIF-8 and CV were successfully immobilized in PANAM's porous structure, which effectively enriched active sites and realized efficient anchoring of CV. The triple synergy of ZIF-8, PANAM and polymer matrix enables long-term CV release. Compared with other PVA composite pads containing the same CV content, PANAM@ZIF-8@CV/PVA presented a superior long-term slow-release effect and thus exhibited excellent antioxidant and long-lasting antibacterial properties after 30 days of storage. During 15-day blueberry storage, this composite pad reduced respiratory intensity and weight loss while preserving firmness and nutrients. Thus, blueberries retained intact morphology and fresh taste, demonstrating great potential of PANAM@ZIF-8@CV/PVA in long-term blueberry preservation.