Encapsulation of carvacrol in β-cyclodextrin metal-organic frameworks: Improved solubility, stability, antioxidant capacity and controlled release of carvacrol

Abstract

Carvacrol, a phenolic compound found in oregano and thyme, exhibits potent antioxidant activity and is commonly utilized in food applications due to its flavor and fragrance, as well as its capacity to inhibit oxidation and prolong shelf life. However, its application is limited by its low water solubility, low stability and high volatility. This study examines the encapsulation of carvacrol within edible and porous materials, namely cyclodextrin metal-organic frameworks (CD-MOFs), as a means of enhancing its properties. In the present study, β-CD-MOFs were synthesized with varying amounts of carvacrol. The encapsulation efficiency was observed to vary with the ratio of carvacrol to β-CD-MOF, with an improvement in efficiency achieved at higher ratios up to a point, reflecting the capacity of the β-CD-MOF to encapsulate carvacrol molecules effectively before reaching saturation. Morphological examination and X-ray diffraction (XRD) revealed significant structural alterations in the β-CD-MOF following the loading of carvacrol. Fourier-transform infrared (FTIR) spectroscopy served to confirm the successful encapsulation, as evidenced by alterations in the bonding patterns. Thermal analysis revealed shifts in degradation temperatures and the absence of the boiling point peak of carvacrol in carvacrol-loaded β-CD-MOFs (Car/β-CD-MOFs), indicative of successful encapsulation and enhanced thermal stability. The antioxidant capacity of carvacrol was found to increase significantly upon encapsulation within β-CD-MOFs, as evidenced by antioxidant assays. Solubility and release profile studies demonstrated an improvement in the dissolution and controlled release behavior of carvacrol. These findings collectively highlight the potential of β-CD-MOFs as effective carriers for enhancing the functional properties and applications of carvacrol.