AbstractFragrance compounds and essential oils are currently extracted more effectively and selected for a variety of purposes thanks to research over decades by industry and scientists working on medicines, food and cosmetics. Among the essential oils, peppermint oil is most widely known for its antimicrobial activity and as a multifunctional flavor compound. In this study, the flavor retention and properties of peppermint oil in the alginate biopolymer during encapsulation and storage are investigated. For this purpose, microânanocapsules are produced and characterized according to their structure, mean particle size and size distribution using a scanning electron microscope (SEM) technique. The stability of the essential oil during the encapsulation process is assessed using thin-layer chromatography (TLC), gas chromatographyâmass spectrometry (GCâMS), thermogravimetric analysis (TGA) and Clevenger. The antimicrobial activity of microânanocapsules was evaluated using the Gram-negative bacteria Escherichia coli and the Gram-positive bacteria Staphylococcus aureus. It is demonstrated that the process of encapsulation is a suitable method for protecting peppermint natural oil.Keywords: microânanocapsulesencapsulationantimicrobial activitypeppermint oilsodium alginate AcknowledgementThe authors are grateful to Dr. Hosein Zeinali from Isfahan Research Center for Agriculture and Natural Resources.