Development of folic acid and silver nanoparticle modified Cu-based metal–organic framework with enhanced ethylene adsorption and moisture resistance for active fruit packaging

A Cu-based metal–organic framework called HKUST-1 holds critical potential for minimizing postharvest fruit waste by regulating C 2 H 4 concentration. However, their practical application in food packaging remains constrained by structural instability and diminished C 2 H 4 adsorption under high humidity. Here, we improved the hydrophobicity and gas adsorption performance of HKUST-1 with folic acid and silver nanoparticles (AgNPs) using a simple post-synthetic modification strategy. The moisture resistance was significantly enhanced with water contact angle increasing from 55.03° to 103.70°. For HKUAg-1, the C 2 H 4 adsorption capacity increased up to 126.66 cm 3 /g STP, showing a 10 % increase compared with HKUST-1. For the modified material, Cu 2 ⁺ and AgNPs serve as the primary adsorption sites, while folic acid functions as a secondary site that further enhances C 2 H 4 adsorption. Finally, HKUAg-1 was applied to bananas, and the results showed that under 90 % relative humidity, the fruits retained a yellow-green appearance up to day 7. Starting from day 3, HKUAg-1 significantly reduced weight loss, C 2 H 4 production, respiration rate, and downregulated pectin esterase and pyruvate kinase activities. The results suggest that HKUAg-1 has great potential for use in active packaging to delay ripening and extend the shelf life of bananas even under high-humidity conditions.