An inclusion complex of hexahydro--acids (HBA) and 2-O-methyl--cyclodextrin (M--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 ((HNMR)-H-1), and scanning electron microscopy (SEM). Results showed that the HBA molecule resided within the M--CD cavity. The water solubility test indicated that the effect of the M--CD encapsulation extended beyond increasing the solubility of HBA. Furthermore, the antibacterial activity of the HBA/M--CD inclusion complex, pure HBA, and M--CD against different food-related microorganisms was determined by an agar diffusion assay. Particularly, the HBA/M--CD inclusion complex exhibited better antibacterial activity against Listeria monocytogenes. These results suggest that incorporation of the HBA/M--CD inclusion complex in food might effectively inhibit L. monocytogenes growth.