Nanoemulsion of cinnamon essential oil Co-emulsified with hydroxypropyl-β-cyclodextrin and Tween-80: Antibacterial activity, stability and slow release performance

Essential oils (EOs) are gaining great interest as alternatives to synthetic food preservatives due to their antimicrobial activity. However, EOs are hydrophobic and easy to evaporate. In this research, EOs were encapsulated in nanoemulsions with the aid of hydroxypropyl-β-cyclodextrin (HPCD) to protect the ingredients and sustain the release, so as to exert long-term antibacterial effects. The influence of HPCD and its concentration on cinnamon essential oil (CEO) nanoemulsion formation, antibacterial activity, release property and stability was investigated. The results showed that HPCD reduced the particle size of nanoemulsion as the concentration of Tween 80 ranged from 2 to 4 g/L. However, HPCD addition showed adverse effect as the content of Tween 80 was 5 g/L. Antibacterial tests against Escherichia coli and Staphylococcus aureus demonstrated that the addition of HPCD contributed to the increase of antimicrobial activity of CEO nanoemulsions and showed the best effect when the concentration of HPCD was 30 g/L. The release experiment proved the slow-release ability of HPCD, and showed that the cavity of HPCD helped to reduce the loss of CEO, thus delayed the release time and enhanced the antibacterial effect. Meanwhile, the use of HPCD contributed to the storage stability of the emulsion at 4, 25, and 40 °C, and the nanoemulsion remained stable during a storage period of 60 days.