We investigated organogel formation in dispersions of CW in safflower oil (SFO). Candelilla wax (CW) has as its main component hentriacontane (78.9%), a n-alkane with self assembly properties in organic solvents (i.e., vegetable oils). Results showed that, independent of the cooling rate (i.e., 1°C/min and 10°C/min) and gel setting temperature (T set ), the CW organogels observed a thermoreversible behavior. This was evaluated by the behavior of thermal parameters that characterized organogel formation (gelation temperature, T g ; heat of gelation, DH g ) and melting (melting temperature, T p ; heat of melting, DH M ) after two heating-cooling cycles. For a given CW concentration (i.e., 0.5, 1.0, and 3%), the magnitude of DH M and T p and the structural organization of the organogel, depended on the cooling rate, the thermodynamic drive force for gelation, and the annealing process occurring at high T set (i.e., 25°C). At T set of 25°C the microplatelet units that formed the organogel aggregated as a function of storage time, a process that resulted in an increase in organogel hardness. In contrast, at T set of 5°C annealing occurred in a limited extent, but gels had higher solid fat content and microplatelet units of a smaller size than the gels obtained at 25°C. The result was a threedimensional network with greater hardness than the one obtained at 25°C. The 3% CW organogels showed no phase separation up to 3 months at room temperature, with textures of potential use by the food industry.
The thermo-mechanical properties of organogels developed by a complex mixture of n-alkanes present in candelilla wax (CW) were investigated and compared with the ones of organogels developed by a pure nalkane, dotriacontane (C 32 ). In both cases, the liquid phase used was safflower oil high in triolein (SFO) and the variables studied were two levels of gelator concentration (1 and 3%), cooling rates of 1 and 10 7C/ min, and two gel setting temperatures, 5 and 25 7C (T set ). Based on comparisons of the organogels made with C 32 , the presence of minor molecular components in CW had a profound effect on the crystal habit of the n-alkanes in CW-based organogels, and therefore on their physical properties. Thus, independent of the cooling rate and T set , C 32 showed a higher solubility and higher self-assembly capability in the SFO than CW. Nevertheless, for the same gelator concentration and time-temperature conditions, C 32 organogels had lower G' profiles than CW organogels. Additionally, independent of the type of gelator, more stable organogel structures were developed at T set = 5 7C and using the lower cooling rate. The rheological behavior of the organogels was explained considering the formation of a rotator phase by the n-alkanes, its solid-solid transition, and their dependence as a function of the cooling rate and T set . The results here obtained showed that it is possible to gelate SFO through organogelation with CW and without the use of trans fats.
Using safflower oil as the liquid phase, we investigated the organogelation properties of stearic acid (SA), (R)-12-hydroxystearic acid (HSA), and different primary and secondary amides synthesized from SA and HSA. The objective was to establish the relationship between the gelator's molecular structure, solid content, and gels' microstructure that determines the rheological properties of organogels developed at two cooling rates, 1 and 20 °C/min. The results showed that the presence of a 12-OH group in the gelator molecule makes its crystallization kinetics cooling rate dependent and modifies its crystallization behavior. Thus, SA crystallizes as large platelets, while HSA crystallizes as fibers forming gels with higher solid content, particularly at 20 °C/min. The addition to HSA of a primary or a secondary amide bonded with an alkyl group resulted in gelator molecules that crystallized as fibrillar spherulites at both cooling rates. Independent of the cooling rate, gels of HSA and its amide derivatives showed thixotropic behavior. The rheological properties of the amide's organogels depend on a balance between hydrogen-bonding sites and the alkyl chain length bonded to the amide group. However, it might also be associated with the effect that the gelators' molecular weight has on crystal growth and its consequence on fiber interpenetration among vicinal spherulites. These results were compared with those obtained with candelilla wax (CW), a well-known edible gelling additive used by the food industry. CW organogels had higher elasticity than HSA gels but lower than the gels formed by amides. Additionally, CW gels showed similar or even higher thixotropic behavior than HSA and the amide's gels. These remarkable rheological properties resulted from the microstructural organization of CW organogels. We concluded that microstructure has a more important role determining the organogels' rheology than the solid content. The fitting models developed to describe the organogels rheological behavior support this argument.
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