Interfacial studies of essential oil—water systems
Christophe Arneodoa,
Adam Baszkina,
, Jean Pierre Benoita,
Roland Fellousb
and Curt Thies
c
a
Physico-Chimie des Surfaces et Innovation en Pharmacotechnie, UA CNRS 1218,
Centre d'Etudes Pharmaceutiques, 5 rue Jean-Baptiste Clément, 92296
Châtenay-Malabry France
b Laboratoire de Chimie
des Arômes, Faculté des Sciences, Université de Nice France
c Biological Transport Laboratory, Washington
University, St. Louis, MO U.S.A.
Received 17 November 1987; accepted
27 June 1988. Available online 18 January 2002.
Abstract
The surface tension of mint, lemon and orange oils and the
interfacial tension of these oils against water were investigated by the
Wilhelmy plate method. Variation of these tensions as well as variation of the
surface tension of waters after prolonged contact with the oils were measured as
a function of time and temperature. Spreading coefficients Sow
calculated from these data show that the spreading tendency of these oils, in
the temperature range 30–50°C, is in the order: orange oil> lemon oil>
mint oil.
Combined gas chromatography and mass spectroscopy
analytical data reveal a high concentration of mint oil constituents in water
equilibrated with this oil. Adsorption of these surface-active species at the
air/water interface considerably lowers its surface tension. Positive
temperature coefficients of the surface tension of this water and of the mint
oil/water interfacial tension are attributed to the change in chemical
composition occurring at these interfaces during heating.
Lowering of the interfacial tension at orange oil and lemon
oil/water interfaces was observed when these interfaces were heated. This may be
attributed to the interfacial adsorption of 8-p-menthene-1,2-diol present
in the waters equilibrated with orange and lemon oils.
The data obtained may be indicative of phenomena observed
during encapsulation of these essential oils by the complex coacervation
procedure.
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Colloids
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