Microstructure
Micrographs were obtained with a polarized light filter (10X objective), where the birefringence of the structures formed by the MY is present (Fig. 6). More crystalline structures were found in the SAT systems. This is due to the fact that a higher concentration of MY provides more nucleation points from which the formation of fibrillar crystalline structures occurs, which in turn form the three-dimensional network that immobilizes the liquid oil. Gelator saturation in SAT systems affects the crystalline units in oleogels, this can trigger a decrease in their structural integrity in the initial crystallization process, due to the increased nucleation-crystallization rate, resulting in lower nvalues due to the formation of individual crystal lattices (Table 4). This can be understood as a constraint on network structuring, since individual networks will exhibit less bonding between their structures in the long term. The nucleation rate is closely related to the number of structural elements in an oleogel.
In Figure 6, a higher degree of structuring is observed in CN systems, because the presence of MY promotes early crystallization of the oil at ambient temperature, even at low concentrations (MGC). A better distribution of crystalline structures throughout the plane can be beneficial to obtain desired solid properties, however, an oversaturation of the same can also result in a high hardness and brittle system. From an image analysis, fractal dimensionality values were determined by the correlation method (FD) with high R2 values (Table 4). Fractal dimensionality is an index that points out the crystalline mass distribution in the lattice of an oleogel. All systems present ≈2 values, it is worth mentioning that the geometry of a growing crystal is not determinant of its dimensionality due to the fact that nucleation can be homogeneous or heterogeneous. The DF values reported here are lower than those reported by Palla et al. (2019), with a saturated monoglyceride concentration in a high oleic oil. Differences can be found between the Avrami and FD values of n (Table 4). The geometrical growth of a crystalline structure, in turn, is not independent of the MY concentration, since a higher concentration of gelator in a mostly saturated solvent promotes heterogeneous crystallization from the first structures formed also inducing the sporadic generation of new nucle.