Characterization of novel nanoemulsions, with improved properties, based on rosemary essential oil and biopolymers

Nowadays, it is of great interest to develop stable and sustainable formulations that act as nanocarriers of active ingredients. In this work, the droplet size distribution, rheology and physical stability of nanoemulsions with improved properties containing rosemary essential oil and biopolymers as a function of the concentration of these polysaccharides were investigated.

Mean diameters below 150 nm were achieved, indicating nanostructures were obtained. Regardless of gum type, a gel-like structure and a shear thinning behaviour was achieved. In addition, an increase of G', G″ and viscosity and a decrease of J₀ , J₁ , J₂ , λ₁ and λ₂ with increasing gum concentration were observed, due to the formation of a three-dimensional network in the aqueous phase. Slight differences between nanoemulsions containing welan or xanthan were found. Creaming, depletion flocculation and gel aggregation were the main destabilization processes at low, intermediate and high gum concentration, respectively. A 0.4 wt% gum nanoemulsion exhibited the best physical stability.

These stable and sustainable nanoemulsions with improved rheological properties contribute to the development of biodegradable and non-toxic food or agrochemical products. © 2020 Society of Chemical Industry.