Title Strategies for reducing Ostwald ripening phenomenon in nanoemulsions based on thyme essential oil
Authors Trujillo-Cayado, Luis A. , SANTOS GARCÍA, JENIFER, Calero, Nuria , Alfaro-Rodriguez, Maria-Carmen , Munoz, Jose
External publication Si
Means J Sci Food Agric
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
JCR Impact 3.63900
SJR Impact 0.78200
Publication date 15/03/2020
ISI 000504933500001
DOI 10.1002/jsfa.10181
Abstract BACKGROUND White thyme essential oil, which can be incorporated in clean-label and food emulsion-based products, is a natural antimicrobial agent. However, emulsions containing essential oils commonly undergo Ostwald ripening as the main destabilization process. The main objective of this work was to evaluate various strategies for the inhibition of Ostwald ripening so as to develop stable nanoemulsions containing white thyme essential oil as food preservative and Kolliphor EL as surfactant. RESULTS In a first approach, the influence of the surfactant/dispersed phase ratio and the number of cycles through a microfluidizer on droplet size distribution was evaluated. Unfortunately, these emulsions underwent Ostwald ripening, which was demonstrated by the application of the Lifshitz-Slyozov-Wagner theory. In order to reduce this destabilization mechanism, two different techniques based on the modification of the formulation (addition of rosin gum or Aerosil COK84) were analysed using laser diffraction and multiple light scattering techniques. The addition of rosin gum inhibited the Ostwald ripening mechanism, but only partially. Conversely, the incorporation of Aerosil COK84 to the continuous phase led to a gel-like rheological behaviour which seemed to practically avoid Ostwald ripening. CONCLUSIONS Aerosil particles cover the droplets and form a three-dimensional network suggesting a Pickering stabilization, which was confirmed using transmission electronic microscopy. The results confirmed the role of Aerosil COK84, not only as a thickener or gelling agent, but also as an Ostwald ripening inhibitor. (c) 2019 Society of Chemical Industry
Keywords antimicrobial; food preservative; essential oil; Ostwald ripening; Pickering emulsion
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