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Small deformation rheology was used at a controlled strain of 0.05% and frequency from 1 to 100 Hz to obtain G′, G″, and tan(δ) values for ethylcellulose oleogels of various compositions. Significant increases in both G′ and G″ were noted in oleogels prepared with 100 cP ethylcellulose as compared to 45 cP, yet no significant differences in tan(δ) were observed among gels containing the same type of vegetable oil. Oleogels prepared with increasing polymer concentration showed a significant increase in G′ only when the concentration exceeded 13%. When the surfactant sorbitan monostearate was incorporated at a level of 3.33%, a significant increase in tan(δ) was seen, indicating a decrease in elasticity of these oleogels. Cryo-scanning electron microscopy was successfully utilized to image the internal polymer network of ethylcellulose oleogels, which contained small oil-filled pores of approximately 3.0–4.5 μm in size lying between the interconnected polymer chains. Decreases in pore sizes were observed with increasing polymer concentration, oil unsaturation, and high levels of surfactant incorporation. No significant change in pore size was seen among gels made with different polymer viscosities, signifying an alternate mechanism for changing oleogel hardness. De-oiled ethylcellulose oleogels were also successfully imaged using fluid-phase contact mode atomic force microscopy. The striking similarity in the images obtained by both these methods strongly suggests the morphological features of the oleogels are preserved through the sample preparation procedure. Ethylcellulose xerogel micrographs were shown for the first time, and also contain some regions with pores similar in morphology to those identified in micrographs of the partially de-oiled oleogels.

Publisher Summary This chapter focuses on structured emulsions and edible oleogels, two potential solutions to the trans fat dilemma. To understand why these are potential solutions, the chapter presents some background information in regard to how specific fatty acids affect the cardiovascular health. Although many promising solutions to Trans Fatty Acids (TFAs) have been proposed and are currently in use, development is still required to ensure that trans fats are not just simply being substituted with something that is equally, or similarly, harmful. It should be attempted to develop solutions that not only provide all the requirements of a viable substitute, but also ideally contain components or ingredients that actually improve the cardiovascular health, such as phytosterols or polyunsaturated fatty acids. With the development of many functional and comparatively healthy replacements over the past five years, such as oleogels and structured emulsions using monoglycerides, it is possible to overcome the trans fat problem in the near future.

Ethylcellulose has been recently shown to be an excellent organogelator for vegetable oils. The resulting gels maintain the fatty acid profile of the vegetable oil used, but posses a solid-like structure that can be useful for the replacement of saturated fats in food products. Texture profile analysis and the back extrusion technique were used to assess the mechanical properties of canola, soybean, and flaxseed oil oleogels consisting of 10% ethylcellulose and 90% vegetable oil. Oils with a higher degree of unsaturation were shown to produce harder gels. Oleogels containing ethylcellulose of three molecular weights and reduced polymer concentrations from 4-10% ethylcellulose were also tested using the back extrusion technique, resulting in an increase in gel strength as polymer concentration and molecular weight increased. Therefore, oleogel strength was shown to be dependant on polymer molecular weight, concentration, and the fatty acid composition of the vegetable oil. Scanning electron microscopy was also used to provide a greater understanding of the gel's microstructure. In addition, frankfurters were made using canola oil oleogels to assess the possibility for replacement of the more highly saturated animal fat in such a product. Cooked frankfurters made with oleogels showed no significant differences in chewiness or hardness compared to the control products made with beef fat. These results provide the first in-depth characterization of ethylcellulose oleogels, and could potentially aid in the design/manufacture of ethylcellulose oleogels with specific textural properties to replace saturated fat in a variety of food products.