Production of clove oil nanoemulsion with rapid and enhanced antimicrobial activity against gram‐positive and gram‐negative bacteria

Abstract The clove essential oil is a natural antioxidant and antimicrobial with potential applications in many fields of the industry. Nanoemulsions (NEs) with Dp ~135 nm loaded with clove oil (CO) and crodamol were produced by ultrasound. The presence of crodamol in formulation increased droplet size homogeneity and prevented the diffusional degradation with the consequent increase in the stability. The formulation containing 7 mg/mL of CO presented a high surface area and exhibited the lowest minimum inhibitory concentration against gram‐positive and negative bacteria when compared to the free CO, indicating an increase in the antimicrobial activity with the reduction of the droplet size to the nanometric range. Microbial inhibition kinetics showed a fast action of the NE in the inactivation of microorganisms tested. The antioxidant activity was evaluated and both free and nanoemulsified CO remained with antioxidant potential around 90%. The present work produced CO NE with rapid and increased bioactivity, and strong antioxidant potential, becoming an effective and natural alternative for future applications in food formulations. Practical applications The clove essential oil is very interesting to the food and pharmaceutical industries due to the great antimicrobial and antioxidant properties. However, some limitations are related to its hydrophobic character, which limits the application in food formulations due to the low solubility in aqueous media. The essential oils nanoemulsions can be a great alternative to improve the oil solubility, increase the contact area, and protect the bioactive components that are present in the essential oil. Although some studies have been showing the great potential of the essential oil nanoemulsions, the investigation around the reduction of the emulsion droplet diameter, considering the relation between the nanometric range and the increase in the bioavailability and biological activity, is a critical issue to enable their application in food formulations.