Cinnamon Essential Oil Nanocellulose-Based Pickering Emulsions: Processing Parameters Effect on Their Formation, Stabilization, and Antimicrobial Activity

Abstract

This work aimed to prepare nanocellulose-based Pickering emulsions using cinnamon essential oil. Different formulations were investigated by varying the preparation time, homogenization speed, oil and nanocellulose concentration, and morphology. The emulsions were first characterized by droplet size, morphologies, and storage stability. The Design of Experiments (DoE) was used to evaluate the parameter’s effects on the emulsions’ stability, and the emulsions with optimum particle size and stability were evaluated by antimicrobial activity. The more stable emulsions required higher energy in the system to obtain efficient emulsification. The cellulose nanocrystal (CNC) emulsions showed a 30% oil volume as a constant to obtain a low creaming index (34.4% and 42.8%) and zeta potential values around −29 mV, indicating an electrostatic stabilization. The cellulose nanofiber (CNF) emulsions showed 100% stability after a month using a 20% oil volume as a constant and Zeta potential values around −15 mV, indicating a steric stabilization. CNF-emulsions’ inhibition halos for Bacilus subtilis were 30.1 ± 3.7% smaller than those found in CNC-emulsions (65 ± 2.9 mm), while Pseudomonasaeruginosas almost do not present differences in the inhibition halos. These results suggest that the nanocellulose morphology may promote a regulation on the EO migration to the medium, as well that this migration ratio does not affect the bacteria.

Durable Nanocellulose-Stabilized Emulsions of Dithizone/Chloroform in Water for Hg2+ Detection: A Novel Approach for a Classical Problem

“…The other phase (serum) accounted mainly for CNFs and water. Its height decreased with the concentration of stabilizer, as commonly found in most reports on Pickering stabilization. , For CNF consistencies equal to or higher than 0.20 wt %, no serum phase was appreciated and the whole mixture was emulsified. This is shown in Figure , along with the intensity-average hydrodynamic diameter ( d H ) of organic dispersed droplets.…”

Chemical Stabilization behind Cardamom Pickering Emulsion Using Nanocellulose

“…Nanocellulose (CNF or CNC) was mixed with water to adequately dilute the suspensions to 0.5 or 1 wt% and ultrasonicated (40 W, 23 kHz) for 2 min in an ultrasonic bath to prepare a dispersed aqueous solution (0.5 or 1 wt%). The nanocellulose concentration was selected based on an extensive literature search and several experimental tests previously conducted in this area [29,30]. Then, cardamom essential oil was added for the Pickering emulsion's preparation.…”

“…For the CNF emulsions, the Herschel-Bulkley rheological model was applied, and the parameters are presented in Figure 2, which indicate that, at rest, the materials have the formation of structures similar to a solid, possibly indicating that there are complex interactions between the components of the emulsions at the interfaces between the droplets of oil and water [30,31]. Both samples showed n values between 0 and 1, confirming the pseudoplastic behavior [32], the most common non-ideal behavior exhibited for commercial emulsions, since low n values facilitate oil dispersion and improve its bioactivity [22,27].…”

Encapsulation of Thymol and Eugenol Essential Oils Using Unmodified Cellulose: Preparation and Characterization

“…In contrast to surfactants, which are dynamically adsorbed and desorbed at the interface, bioparticles adsorb irreversibly to it, forming the so-called “Pickering emulsions” [ 18 , 19 ]. While stabilization by the Pickering mechanism is widely used [ 17 , 18 , 20 ], it is less suited for encapsulation of EOs in applications that require a more continuous protective coating [ 21 , 22 , 23 ].…”