Controlled Release of Thymol by Cyclodextrin Metal-Organic Frameworks for Preservation of Cherry Tomatoes

Thymol is a phenol monoterpene with potential antifungal, antioxidant and antibacterial activities. Due to the low water solubility and high volatility of thymol, encapsulation serves as an effective tool during application. In the present study, cyclodextrin (CD)-based metal-organic-frameworks (MOFs) were synthesized using α-CD, β-CD, and γ-CD as organic building blocks, and further complexed with thymol to produce three CD-MOF-THY inclusion complexes (ICs). The encapsulation content, release kinetics and fruit preservation effect of ICs were analyzed. Results showed that thymol was well embedded in γ-CD-MOFs, with the highest encapsulation content of 286.7 ± 8.4 mg/g. Release kinetics revealed that CD-MOFs exhibited a controlled release effect toward thymol for 35 days. The release kinetics of three ICs fit the Rigter-Peppas model well, with γ-CD-MOF-THY showing the lowest release rate constant of 2.85 at 50 °C, RH 75%. Moreover, γ-CD-MOF-THY exhibited a remarkable preservation performance on cherry tomatoes with the lowest decay index (18.75%) and weight loss (5.17%) after 15 days of storage, suggesting this material as a potential fresh-keeping material for fruit and vegetable preservation.