Fabrication, structure and properties of pullulan-based active films incorporated with ultrasound-assisted cinnamon essential oil nanoemulsions

Abstract

• Cinnamon essential oil nanoemulsions (CEON) were prepared by ultrasound treatment. • Pullulan-based active films incorporated with CEON were successfully fabricated. • The addition of CEON led to improved film flexibility and water barrier property. • Small size and even distribution of oil droplets caused higher retention of CEO. • Higher CEON content enhanced antibacterial activity of films but increased CEO loss. In this study, cinnamon essential oil (CEO) nanoemulsions were prepared using different concentration of Tween 80 and various acoustic energy input and the effects of nanoemulsion addition on the structure and properties of pullulan-based active films were investigated. Results revealed that CEO nanoemulsion containing 6 % Tween 80 under 10 min of ultrasound treatment exhibited the smallest droplet size (60 nm) and highest storage, centrifugation and heat stability. Pullulan-based films incorporated with above nanoemulsion showed the lowest water vapor permeability (0.050 g·m −1 ·kPa −1 h −1 ) and highest elongation at break (5.4 %) due to the hydrophobic and plasticizing effects of CEO. The active film also owned the greatest ability of CEO retention and bacteriostasis because of the smallest size and most uniform distribution of oil droplets in the film matrix. Meanwhile, increasing concentration of CEO nanoemulsion improved antibacterial activities of composite films, but increased CEO loss from films during drying and ambient storage.