Evaluation of Ethyl Cellulose oleogel Functionality as Shortening Substitute in the Formulation of Cake with Low Saturated Fatty Acid Content

Shortening is an important ingredient of bakery products, especially the ones with less  developed gluten network like cakes and cookies . Shortening thermo-rheological properties are related to the presence of high levels of saturated fatty acids which have the capability of making crystals at room temperature which melt during baking. Consumption of high saturated fatty acids increases the risk of coronary disease. Moreover, hydrogenation is a usual technique for elevating the saturated fatty acid content of vegetable oils. Lowering the saturated fatty acid content of a shortening results in the shortening with less functionality. Transition of an oil physical properties to those of a semi-solid structure can be done using low- or non-digestible oil gelators called oleogelation. Ethyl cellulose is a polymer with oil gelation capabilities at low concentrations. However, its oleogels are firm and brittle, so some low-molecular-weight gelators can improve its texture and increase its plasticity to mimmic commercial shortening functionality. In this study, the functionality of an oleogel based on ethyl cellulose, stearyl alcohol, stearic acid and sorbitan monostearate was evaluated as commercial shortening substitute in cake formulation.  

Based on previous studies and preliminary experiments, an optimized oleogel formulation was prepared as shortening, composed of ethyl cellulose (6.4%), stearyl alcohol:stearic acid (70:30) (7.5%), sorbitan monostearate (0.1%) and canola/soy mixture oil (75:25 ratio) (86%).The gel was formed by heating up the mixture to 150 °C for the complete solvation of the gelator compounds and gradual cooling to room temperature. In the next step, commercial shortening was substituted with the oleogel shortening at 0, 25,50, 75 and 100% in the cake formulation. Moisture content, water activity, specific volume, crust color, Lab color space indices based on image processing, porosity based on crumb image analysis, TPA parameters and sensory attributes were determined and compared using one-way analysis of variance and LSD mean comparison test.  

The results showed that there was no significant difference in the moisture content, water activity and specific volume of the cakes prepared with the oleogel shortening with the one prepared with commercial shortening. This reveals that the oleogel shortening functionality was acceptable compared with commercial shortening. In terms of crust color, there was no significant difference in the lightness index (L*) and red-green range (a*) indicators between different samples and only in the yellow-blue range (b*) index, the cake with 100% substitution showed a lower value than the control. For the porosity index, there was no significant difference between the five samples, proving the oleogel shortening can induce sufficient air bubbles generated during batter mixing and its preserving effect during baking. Examining the texture of the cake samples showed that the texture hardness and springiness indices decreased with a rise in the level of commercial shortening substitution, while the cohesiveness index did not differ significantly. The latter  indicated that the oleogel shortening effectively shortened the gluten network; thus, it can be said that the same commercial shortening functionality is attainable using less oleogel shortening content. Furthermore, as the percentage of the commercial shortening substitutes increased, due to texture softening, the chewing energy of the samples decreased resulting in a better mouthfeel. Finally, sensory evaluation of the cake samples did not show a significant difference in taste, texture, appearance, color and overall acceptance based on scores obtained from ten untrained evaluators. In conclusion, the use of oleogel shortening instead of commercial shortening with high saturated fatty acid content in cake formulation not only can result in a cake with acceptable properties at 50% replacement level, but also can replace commercial shortening even up to 100%.The latter just lead to a softer texture. Optimization of the cake formulation based on the oleogel shortening would specifically result in a cake with better properties, while it has significantly lower saturated fatty acid content and nearly zero trans fatty acids.