Eugenol‐Loaded Microemulsions: Characterization, Antibacterial Activity, and Fresh‐Cut Lettuce Sanitization

Abstract

ABSTRACT Eugenol, a major bioactive compound present in various essential oils with substantial antibacterial activity, has limited application in food industries due to its low water solubility. To address this limitation, a microemulsion system was developed utilizing Tween 80 as a surfactant and lactic acid as a co‐surfactant to facilitate the delivery of eugenol. The resulting microemulsion underwent physicochemical characterization, antibacterial evaluation, and sanitation trials on fresh‐cut lettuce. Phase analysis revealed three distinct types of microemulsions with stability and dispersibility: water‐in‐oil with 0%–20% water, bicontinuous with 30%–60% water, and oil‐in‐water with 70%–90% water. Antibacterial assays indicated minimum inhibitory concentrations of 0.5 mg/mL for Staphylococcus aureus and 0.25 mg/mL for Escherichia coli , along with minimum bactericidal concentrations of 1 and 0.5 mg/mL, respectively. Furthermore, the microemulsion at 1 mg/mL exhibited rapid bactericidal effects against both bacterial strains, achieving a population reduction of over 6‐log units within 10 min. In refrigerated fresh‐cut lettuce sanitation experiments, microemulsion concentrations of 0.25, 0.5, and 1 mg/mL effectively suppressed the number of total microbes, mold, and yeast, with 0.5 mg/mL treatment being most effective in maintaining lettuce quality and freshness. Additionally, these treatments contributed to the preservation of vitamin C content, chlorophyll level, and color stability. Overall, the results demonstrate that eugenol microemulsions hold strong potential as green sanitizers for vegetables, offering a promising avenue to enhance food safety and quality.