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

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.

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Linalool Essential Oil/Nanocellulose-Based Pickering Emulsions: An In-Depth Investigation of Processing Parameters

10.21203/rs.3.rs-455128/v1 ◽

2021 ◽

Author(s):

Alana Gabrieli de Souza ◽

Jéssica de Souza Marciano ◽

Rafaela Reis Ferreira ◽

Eder Ramin de Oliveira ◽

Derval dos Santos Rosa

Keyword(s):

Essential Oil ◽

Electrostatic Interactions ◽

Processing Parameters ◽

Solid Particles ◽

Pickering Emulsions ◽

Optimum Parameters ◽

Maximum Stability ◽

Oil Concentration ◽

And Storage ◽

Ideal Process

Abstract This study aims to prepare nanocellulose-based emulsions using linalool essential oil using different processing parameters and correlating them with emulsions' stability and particle size. The investigated parameters were cellulose morphology (CNC or CNF) and concentration (0.5 or 1 wt%), essential oil concentration (20 or 30% v/v), homogenization speed (10,000 or 12,000 rpm), and time (3 or 7 minutes). The emulsions were tested by droplet size, morphology, and storage stability. The Design of Experiments (DoE) was used to understand each parameter's effects in the emulsions' characteristics and the statistical results. Each nanocellulose morphology presented a type of stabilization in emulsions and different ideal process parameters. CNC-emulsions showed as optimum parameters 30% essential oil and 7 minutes preparation, reflecting the higher necessary energy for the efficient CNCs adsorption in the O/W interface, and the maximum stability was ~ 50% by electrostatic interactions. CNF-emulsions showed optimum parameters 1% CNF and 12,000 rpm homogenization speed, reflecting the necessary parameters to convert the suspensions into gels where the droplets are well-coated by the fibers. This study is a pioneer in an in-depth understanding of the processing parameters' impact on emulsion stability and will be a guideline for future studies with different solid particles and oil phases.

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