We investigated the development of water-in-oil (W/O) emulsions just using CW, evaluating the effect of the water to CW oleogel ratio (40:60, 50:50, 60:40) and, at each ratio, the effect of the CW concentrations (0.75% to 3%). The emulsions were developed by shearing (60 s at 25°C) using an ultra-turrax type homogenizer. The emulsions were immediately evaluated and after 20 days of storage (25°C) for microstructure, water droplet diameter, emulsion stability through DSC freeze/thaw cycles, rheological properties, and X-ray measurements. The results showed that, at all water to oleogel ratios studied the CW developed structured W/O emulsions where the surface-active components of the CW (i.e., triterpenic alcohols, aliphatic alcohols, and fatty acids) stabilized the oil-water interface, while the n-alkanes and long chain esters formed an oleogel in the oil phase. Although, independent of the storage time, all the CW emulsions showed a frequency independent rheological behavior, after applying a strain above the G’-G” cross point, the 40:60 and 50:50 emulsions with 1.5% to 3% CW concentration showed the better rheological behavior and were the most stables, even after two freeze-thaw cycles. In particular, the 40:60 and 50:50 emulsion with 1.5% CW had a recovery profile similar to commercial mayonnaise. In contrast, independent of the CW concentration, the 60:40 emulsions showed the lowest recovery profiles and higher instability to freeze-thaw cycles. These results indicated that the CW is a multi-functional material able to develop structured W/O emulsions useful for the formulation of trans-free, stable low-fat edible spreads.

The initial oleogelation process (microstructuring) as well as the formulation are determinant to obtain the desired characteristics in oleogels with potential application in the industry. The microstructuring process in oleogels has been extensively studied by means of techniques highly sensitive to thermal variations, such as differential scanning calorimetry (DSC). However, there are other readily available techniques and equipment that can be employed to perform similar evaluations. Non-isothermal nucleation kinetics by spectrophotometric methods can be used as alternatives to basic crystallization studies in oleogels. Therefore, in this research a comparison of both techniques is presented, highlighting their similarities, advantages and limitations, in the study of the microstructure of oleogels. Oleogels were obtained with a minimum concentration of gelator and another saturated one, using vegetable oils of different degrees of saturation. The crystallization profiles of the oleogels were obtained by DSC, a non-isothermal nucleation kinetics was performed from the molten system and the final microstructure was evaluated by optical microscopy. The Fisher-Turnbull and Avrami model was used to evaluate the behavior during microstructuring. A gap was observed during the crystallization process by DSC which can be evaluated by spectrophotometry. Differences in the microstructuring process were found in both methods due to the temperature ramp used and formulation variables. The results obtained by spectrophotometry indicate that it can be a good alternative, easily accessible in oleogel crystallization studies, when high sensitivity or very specific thermal parameters are not required.

We studied the thermomechanical and microstructural properties of oleogels developed with 2.1 to 15.7 Moles of monoglycerides/Mole of lecithin (MG/LC). The oleogels were developed (15°C) in vegetable (VO) and mineral (MO) oils using at each MG/LC 2% or 4% total mass of gelator. During oleogelation a synergistic MG-LC interaction existed deriving in the development of MG-LC cocrystals even below the gelators’ minimum gelling concentration. The cocrystals delayed the Lα→β polymorphic transition and worked as an active filler of the oleogels’ crystal network. In the VO, the oil with the highest relative polarity, the oleogels were structured by a network of β crystals where the cocrystals acted as an active filler. In the MO, the oil with the lowest relative polarity, the cocrystals’ development was favored while the Lα→β transition occurred just in the 15.7 MG/LC oleogels. Then, at all MG/LC the VO oleogels with 2% or 4% total gelator concentration achieved higher G’ than MO oleogels. However, the presence of β crystals will produce deleterious effects in shorter time in the VO oleogels than in the MO oleogels. In both oils the oleogels with the highest G’ and gel-like rheological behavior were achieved at 8.1 MG/LC, particularly at 4% total gelator concentration. Under these conditions the β polymorph was limited developed in the VO oleogels and completely absent in the MO oleogels. Then, we might tailoring the rheology of MG-LC oleogels with storage stability using as design variables the MG/LC, the total gelator concentration, and the polarity of the oil.