Characterization and antimicrobial activity of a 2-O-methyl-β-cyclodextrin inclusion complex containing hexahydro-β-acids

An inclusion complex of hexahydro-β-acids (HBA) and 2-O-methyl-β-cyclodextrin (M-β-CD) was prepared using the grinding method to improve the water solubility of HBA. Complex formation was assessed using ultraviolet and visible light (UV–Vis) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), nuclear magnetic resonance (1HNMR), and scanning electron microscopy (SEM). Results showed that the HBA molecule resided within the M-β-CD cavity. The water solubility test indicated that the effect of the M-β-CD encapsulation extended beyond increasing the solubility of HBA. Furthermore, the antibacterial activity of the HBA/M-β-CD inclusion complex, pure HBA, and M-β-CD against different food-related microorganisms was determined by an agar diffusion assay. Particularly, the HBA/M-β-CD inclusion complex exhibited better antibacterial activity against Listeria monocytogenes. These results suggest that incorporation of the HBA/M-β-CD inclusion complex in food might effectively inhibit L. monocytogenes growth.