Rheological properties of ethyl cellulose-monoglyceride-candelilla wax oleogel vis-a-vis edible shortenings.

The gelation process, elasticity, and mechanical recovery after shear were studied in mixed oleogels of ethylcellulose (EC), monoglycerides (MG), and candelilla wax (CW). EC oleogels produced without MG showed grainy texture due to incomplete dissolution of crystalline fractions of raw EC in the vegetable oil (150 °C). These fractions were eliminated by dissolving the raw EC/MG mixture in ethanol, evaporating the solvent, dispersing, and dissolving the solid residue in the vegetable oil (150 °C) prior gelation. The EC polymeric network, and MG, and CW crystals had a positive interaction on the elasticity of mixed oleogels. Mixed oleogels produced under static conditions showed a 100 % of elasticity recovery after shearing, a phenomenon associated with an EC interchain hydrogen bonding mediated by hydroxyl groups of MGs. This tentatively resulted from the formation of junction zones of the type EC-[MG]n-EC. The rheological behavior of these olegels was remarkably close to that of commercial shortenings.

Structuration, elastic properties scaling, and mechanical reversibility of candelilla wax oleogels with and without emulsifiers.

The crystal network development, elastic properties scaling behavior, and mechanical reversibility of candelilla wax (CW) oleogels with and without emulsifiers were studied. Saturated monoglycerides (MG) and polyglycerol polyricinoleate (PGPR) were added at 1 or 2 times the critical micelle concentration. Although the micelles of both emulsifiers act as nucleation sites for the mixture of aliphatic acids and alcohols of CW, they did not affect the oleogel's thermodynamic stability. It was established that the crystal network of CW consists of at least two types of crystals, one rich in n-hentriacontane and other rich in aliphatic acids. Both crystals species contributed significantly to the oleogel elasticity. The elastic properties scaling behavior of CW oleogels fitted the fractal model within the weak-link regime. The setting temperature and added emulsifier modified the crystal network fractal dimension. During shearing, oleogels had massive breaking of junction zones, causing the loss of fractality in the crystal network, which in turn decreased the system's elasticity.

Phase behavior, structure and rheology of candelilla wax/fully hydrogenated soybean oil mixtures with and without vegetable oil.

Vegetable oil organogelation is one of the most promising strategies to eliminate trans fatty acids in plastic fats. Organogels prepared with edible wax are stable at refrigerator and room temperature. Some functional properties (i.e., texture) of wax organogels can be improved by adding saturated triacylglycerols. Mixtures of fully hydrogenated soybean oil (FH) and candelilla wax (CW) were studied with and without the addition of high oleic safflower oil (HOSFO). Crystallization and melting behavior, X-ray diffraction, and crystalline microstructure of the mixtures were analyzed. The elastic modulus (G'), and the structural recovery after shear of the organogels were also assessed. Mixtures without HOSFO formed solid dispersions of CW and FH crystals, where up to ~10% CW crystals were incorporated into the FH crystal lattice. The vegetable oil solutions of FH/CW mixtures crystallized from the melt, developed mixed crystal networks composed of FH crystals in the ß polymorph and CW in an orthorhombic subcell packing. As the systems crystallized in the most stable polymorph, only minor microstructural changes were shown along 28days of storage at 25°C. CW and FH crystals showed a synergistic effect on the elasticity of organogels. This was attributed to the large number FH crystals nucleated on the surface of CW crystals. The structural recovery after shear was superior for mixed organogels composed of CW platelets and grainy FH crystals compared to that of CW organogels. A recovery of up to 65.7% the G' of gels formed under static conditions was observed upon shearing.

Determination of absolute threshold and just noticeable difference in the sensory perception of pungency.

Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods. Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently required because "hot" foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds are useful tools in the formulation and development of new food products. These parameters may help in defining how much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding how much more chili pepper is required in a product to produce a perceptible increase in its pungency.