Self-Assembled Liquid Particles: How to Modulate their Internal Structure - Food Colloids: Self-Assembly and Material Science - page 80

022

220

202

202 022 220

300 nm

Figure 10 Cryo-TEM image of MLO-based aqueous TC-loaded dispersion with d ¼ 71.4.
Here, cubosomes with internal Fd3m phase are observed. Inset is an FFT of the
arrowed particle viewed along [111]. A hexagonal motif formed by the { 220 }
reflections is observed

arranged tetrahedrally on a diamond lattice, and 16 smaller reverse micelles of
symmetry 3 m. These discrete aggregates, whose core consists of hydrophilic
aqueous domains, are embedded in a continuous three-dimensional hydropho-
bic matrix (the oil phase). The Fd3m phase appears between the H 2 and W/O
microemulsion phases. For the TC-loaded dispersion with d ¼ 71.4, the cryo-
TEM image shown in Figure 10 reveals the formation of particles with an
internal motif. The FFT (inset of Figure 10) shows a sixfold symmetry, and
therefore the electron beam is very likely parallel to the [111] direction. The
interplanar distance corresponding to the intensity peak in the FFT is 8 nm,

which is in agreement with the presence of {220} reflections leading to a lattice
parameter of

B

22 nm confirming the SAXS analysis.
These particles with self-assembled structured interiors can also be produced
in food-grade systems. We present here a complete temperature-composition
phase diagram for R -( + )-limonene-loaded Dimodan-based particles stabilized
by F127 over the range 1-901C. The phases identified by SAXS and their
location in the temperature- d representation are shown in Figure 11. We
clearly see this new phase inserted between the inverse hexagonal and the L 2
phases. Before eventually reaching the MCP, the particles always first trans-
form into hexosomes, but in the end, above a certain oil content, and depending
on the temperature, they all turn into EME particles. In the case of pure phases,
the hexosome to EME transformation can then occur directly (between 50 and
701C) or indirectly through the MCP (between 1 and 401C) by increasing the oil
content. It is interesting to note that all the particles' internal structures melt
into an L 2 phase at a certain temperature, which is strongly dependent on the
oil content (801Cat d ¼ 100, but only 401Cat d ¼ 70). Above d ¼ 60, the more
oil we add, the lower is the transition. Below this value, we have EME particles
at any temperature. Thus, in any case, increasing the temperature or oil content
will lead in turn to EMEs. The eventual existence of the MCP is consistent with
bulk studies where the location of the inverse cubic I 2 phase was thus far only
found between the H 2 phase and an inverse micellar solution L 2 . This internal
phase behaviour, upon changing the oil/monoglyceride balance, can be

B