Crystallization and Melting Profiles
The thermograms of the vegetable oils and MY are shown in Figure 2. The temperatures of the different exotherms and endotherms of each component were determined. CA presented a crystallization and melting temperature at -55.66±0.17°C and -18.91±0.12°C, respectively. CN presented two crystallization signals, one -3.11±0.27°C and the other at 7.26±0.29°C, this probably due to the composition of triglycerides in CN, which are formed by a lower percentage of PFA that crystallize at lower temperature (Table 1). The melting temperature of CN was at 23.08±0.13°C (Ghosh & Rousseau, 2009). Two exotherms were observed in MY, one from the lamellar state crystallization (63.58±0.03°C) and one from the solid-solid transition Sub-α (11.47±0.16°C). Correspondingly, during heating, Sub-α ⇔ Lα (12.93±0.15°C) and melting (65.52±0.13°C) temperatures were identified. These values are similar to those reported by other authors for commercial monoglycerides, where polymorphic states were identified by X-ray diffraction (López-Martínez et al., 2014). According to some authors (Vereecken et al., 2009), by employing pure compounds individually, the main components of MY have different crystallization and melting points, however, possessing a similar structure palmitic (C16:0) and stearic (C18:0) acid, they can generate a mixed Lα crystallization (López-Martínez et al., 2014), so the proportion in which these are found in Myverol gelator can result in differences in thermal and microstructural properties.
Since MY is the component responsible for gel structuring and formation, an analysis of the changes that its endotherms can present in oleogels with formulation and concentration variables was performed. Changes in the crystallization of were monitored (Fig. 3). In oleogels with MGC it was possible to find MY TC values at 31.30±0.10°C in CA and 28.96±0.19°C in CN (Table 2), these values are very similar to those reported by other authors, in a mixture used of commercial monoglyceride with lecithin (Aguilar-Zárate et al., 2019). However, unlike the exotherm with two peak maxima reported by Aguilar-Zárate et al. (2019), in these systems a single peak maximum is observed, albeit in a more robust exotherm. While these differences may be due to the temperature ramp, it is also due to the difference in the proportions of palmitic and stearic acid. Similarly, a single exotherm was found in the SAT systems (Fig. 3). However, the crystallization of was at a higher temperature ~49°C (Table 2).