Nanoemulsions encapsulating oregano essential oil: Production, stability, antibacterial activity and incorporation in chicken pate

Several essential oils (EO) are efficient inhibitors of foodborne pathogen growth. However, their direct incorporation into food presents technological challenges, because of the possibility of extreme changes to their sensory properties. Such drawbacks can be overcome by encapsulation techniques, such as nanoemulsification. This study produced nanoemulsions encapsulating different amounts of oregano (Origanum vulgare) EO, using the phase inversion temperature method, and their physicochemical stability and antibacterial activity were evaluated. The average droplet diameters of the nanoemulsions were in the range of 35-55 nm, and nanoemulsions containing 5 g EO/100 g nanoemulsion were the most stable over the storage period of 45 days. The nanoemulsions exhibited good antibacterial action demonstrated by the low values in vitro for minimum inhibitory concentration (0.56 and 0.60 mg oregano EO/mL for Staphylococcus aureus and Escherichia coli, respectively, and for minimum bactericidal concentration, 0.90 and 3.32 mg oregano EO/mL for Staphylococcus aureus and Escherichia coli, respectively). The nanodispersions also had a higher antibacterial effect against E. coli than for S. aureus. The incorporation of nanoemulsions in chicken pate did not change the physicochemical characteristics of the meat product. Therefore, the results obtained indicated that nanoemulsions encapsulating oregano EO are suitable to be incorporated into food formulations, such as chicken pate, to prevent and control microbial growth and to extend their shelf life. (C) 2016 Elsevier Ltd. All rights reserved. (AU)