The Carum carvi essential oil contains volatile constituents with noteworthy biological value. These compounds exhibit strong antibacterial and antifungal properties. Nanoemulsions, by increasing the interfacial area between the oil and aqueous phases, enhance the bioactivity of the essential oil and facilitate its access to target tissues. Production of nanoemulsions via subcritical water methods can contribute to improved efficacy of the active materials.This study focuses on the formulation of a Carum carvi essential oil nanoemulsion using a mixture design. In the present work, Carum carvi essential oil was extracted using a Clevenger apparatus, yielding 3.6 mL. Based on a mixture design, the nanoemulsion formulation of the essential oil was optimized within these ranges: essential oil 0.1–0.9 mL, Tween 80 as emulsifier 1–4 mL, and distilled water 20.1–23.9 mL, under subcritical water conditions at 150 °C for 90 minutes.

The results indicate the optimal formulation for oil, emulsifier, and water contents as: 0.62 mL essential oil, 2.75 mL emulsifier, and 21.63 mL water. Dynamic light scattering (DLS) analysis of this formulation showed a mean particle size of 156 nm, polydispersity index (PDI) of 0.196, and zeta potential of −24.1 mV. The application of the product prepared under the optimal conditions, with antifungal activity assessed by diffusion (permeation) method, demonstrated an inhibition of growth of Penicillium expansum by 68.78% and antibacterial activity against the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli, with inhibition zone diameters of 1.6 cm and 1.4 cm, respectively.