Microencapsulation of eugenol molecules by β-cyclodextrine as a thermal protection method of antibacterial action

Abstract

Eugenol is natural oil that has excellent antibacterial properties but cannot be used to fabricate many products that require thermal processing. One possible alternative to the use of the eugenol molecules in high-temperature processes is the encapsulation of these molecules in a structure that is not toxic and is resistant to thermal treatment. This work investigated the encapsulation process of eugenol molecules in β-cyclodextrine and the antibacterial properties of eugenol-β-cyclodextrine (the eugenol-βCD complex) against Escherichia coli and Staphylococcus aureus. The FTIR, DSC, MEV and TGA results show that the encapsulation method is an excellent alternative to increase the thermal stability of eugenol molecules. A value of 241.32L.mol^-1 was determined for the formation constant (Kc) of the eugenol-βCD complex, which confirmed the success of the encapsulation process. The MEV analysis shows the formation of approximately 12μm microcapsules. After the thermal treatment of the eugenol-βCD complex at a temperature of 80°C for 2h, the complex retained significant antibacterial action, which confirms the thermal protection of the eugenol molecules. The minimum inhibitory concentration (MIC) and agar diffusion results show that the microcapsules containing 17.08mmol.L^-1 of eugenol exhibited excellent antibacterial action against Escherichia coli and Staphylococcus aureus after thermal treatment.

Keywords: Antibacterial materials; Microencapsulation of eugenol; Microencapsulation of natural oil; Natural antibacterial materials; β-cyclodextrine.