Curcumin-loaded HKUST-1@ carboxymethyl starch-based composites with moisture-responsive release properties and synergistic antibacterial effect for perishable fruits.

The spoilage of fruit is one of the most important causes of fruit waste. High humidity by fresh fruit respiration leads to bacterial reproduction, which is the key factor of products corruption. Herein, a biological multifunctional film (Cur-HKUST-1@CMS/PVA) for fruits preservation with a high moisture environment was developed by cross-linking carboxymethyl starch (CMS)/polyvinyl alcohol (PVA) with MOF-199 (HKUST-1), and loaded with curcumin. The hydrophilic CMS facilitates water adsorption and moisture can stimulate curcumin release from HKUST-1. HKUST-1 not only acts as curcumin carriers but also forms synergistic antibacterial with curcumin to improve the antibacterial activity of the composites. XRD and SEM demonstrated that moisture disrupts the structure of HKUST-1 and releases curcumin and the results showed that the release of curcumin increased from 25.11 % to 58.32 % after moisture stimulation. In addition, Cur-HKUST-1@CMS/PVA had excellent antibacterial activity and antioxidant ability. As validation, the film can keep pitaya and avocado freshness at least 4 days longer than the control, confirming the effectiveness of Cur-HKUST-1@CMS/PVA in preventing fruit decay. Consequently, Cur-HKUST-1@CMS/PVA is a promising active packaging material for improve the shelf life of perishable fruits.