Nanoencapsulation of Ocimum basilicum L. and Satureja montana L. Essential Oil Mixtures: Enhanced Antimicrobial and Antioxidant Activity.

Background/Objectives: Essential oils (EOs) represent a natural alternative to chemical additives due to their biological activity. This study evaluated the antimicrobial and antioxidant activities of basil and winter savory EO mixtures, their interactions, and the biological potential of chitosan-based nano-encapsulated EO mixtures. Methods: Mixtures of basil and winter savory EOs (ratios 1:1, 2:1, 4:1, 8:1, and 16:1) were analyzed for chemical composition via GC-MS. Antimicrobial activity was assessed using minimal inhibition (MIC) and bactericidal (MBC) concentration assays, and interactions were quantified with fractional inhibitory concentration indices (FICIs). Antioxidant activity was evaluated using the DPPH assay, with combination indices used to interpret interaction effects. Chitosan-based nanoparticles were made with the selected oil mixture (2:1), after which characterization and biological activity were performed. Results: The EO mixture with 2:1 ratio exhibited the strongest joint activity, with synergistic or additive effect against four out of six analyzed microorganisms. Antioxidant activity improved with higher basil proportions, with the 16:1 ratio achieving the lowest EC50 value of 0.052 mg/mL after 120 min and demonstrating synergistic effects at all tested ratios. Higher basil EO content also masked the strong odor of winter savory EO. The biological activity of chitosan-based nanoparticles was increased by encapsulation of the EO mixture (2:1), with an encapsulation efficiency of 75.39%. Conclusions: The EO mixture (2:1) showed best antimicrobial efficacy, with synergistic or additive effects. The nano-encapsulated mixture showed good biological potential with effective and complete odor neutralization. These results indicate the potential of basil and winter savory essential oil mixtures for sustainable food preservation applications.