Characterizing the novel surfactant-stabilized nanoemulsions of stinging nettle essential oil: Thermal behaviour, storage stability, antimicrobial activity and bioaccessibility

Nanoemulsions stabilized with nonionic surfactants (Tween 40, 60, 80) at the different surfactant-to-oil ratios (SORs, 0.25-2.0) were performed and their thermal behaviour, droplet size, storage stability, antimicrobial (minimum inhibitory concentration; MIC) and biological (in vitro digestion extent and bioaccessibility rate) characteristics of stinging nettle essential oil were studied. Thermal stability of the nanoemulsions was studied through a controlled heating-cooling cycle and showed significant differences in their turbidity depending on the type of used surfactant. The Ostwald ripening rate as the main destabilization mechanism at 25 degrees C was lower than that at 4 degrees C after 28 days storage, which was in agreement with the Lifshitz-Slezov-Wagner (LSW) theory. The developed nanoemulsions exhibited a much strong antimicrobial activity in particular against Gram-positive bacteria. A significant increase in the lipolysis extent and bioaccessibility rate was found with a reduction in droplet size at SORs >= 1.0. (C) 2016 Elsevier B.V. All rights reserved.