Microcapsules of a cinnamon, peppermint, and lemon essential oil mix by spray drying: Preparation, characterization and antibacterial functions

Plant essential oils (EO) are increasingly used as food preservatives due to their antibacterial and antioxidant activities. For such applications, EO are commonly microencapsulated to overcome their poor stability, low solubility and dominant aromas. But, typically, individual EO act against only a narrow range of bacterial species. Therefore, in this study, we aimed to develop a microencapsulated preservative using a combination of three EO and to determine its anti-bacterial action against three common food contaminants, viz. Escherichia coli, Salmonella and Staphylococcus aureus, and one, usually, beneficial species, viz. Lactoplantibacillus plantarum. The EO of cinnamon (Cinnamomum cassia), peppermint (Mentha haplocalyx) and lemon (Citrus limon) were combined in the proportions, 1.0 : 1.8: 2.4, respectively and were encapsulated in gelatin-chitosan by spray drying. The particle size, zeta potential, moisture content, and encapsulation rate of the essential oil microcapsules (EOM) were measured. With increasing EOM exposure time, the concentrations of E. coli, Salmonella, S. aureus and L. plantarum decreased by 3, 3, 4, and 5 orders of magnitude, respectively. Cell apoptosis accompanied loss of membrane integrity and permeability, inhibition of lactate dehydrogenase activity and disruption of organic acid metabolism. Gram-positive bacteria (S. aureus and L. plantarum) were more susceptible to those effects of EOM than Gram-negative bacteria (E. coli and Salmonella). It also demonstrates that in applications as preservatives for probiotic foods requiring live L. plantarum, EOM comprising cinnamon, peppermint or lemon EO should be avoided.