Characterization of beta-cyclodextrin inclusion complexes containing essential oils (trans-cinnamaldehyde, eugenol, cinnamon bark, and clove bud extracts) for antimicrobial delivery applications

Abstract

This study aimed to elucidate the physico-chemical characteristics of EO–BCD inclusion complexes and their resulting antimicrobial activity. Cinnamon bark extract, trans-cinnamaldehyde, clove bud extract, eugenol, and a 2:1 (trans-cinnamaldehyde:eugenol) mixture were microencapsulated by the freeze-drying method. EO–BCD complexes were characterized for particle size, morphology, polydispersity index, entrapment efficiency, and phase solubility. All particles showed a spherical shape, smooth surface, no significant differences in size distribution and strong tendency to agglomerate. The entrapment efficiencies ranged from 41.7 to 84.7%, where pure compounds were higher (p < 0.05) than extracts. The oils and their BCD complexes were analyzed for their antimicrobial activity against Salmonella enterica serovar Typhimurium LT2 and Listeria innocua. All antimicrobials effectively inhibited bacterial growth within the concentration range tested, except free eugenol. The EO–BCD complexes were able to inhibit both bacterial strains at lower active compound concentrations than free oils, likely due to their increased water solubility that led to increased contact between pathogens and essential oils. The cinnamon bark and clove bud extract BCD complexes were the most powerful antimicrobials, despite showing the lowest entrapment efficiencies amongst the oils. Results suggest that the application of these antimicrobial complexes in food systems may be effective at inhibiting pathogens.