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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.

Summary Organogelators such as 12-hydroxystearic acid and ethylcellulose have been shown to structure vegetable oils at levels below 8%. The resultant gels retain the fatty acid profile of the vegetable oil, yet provide solid-like properties that can successfully replace saturated fats in a variety of food products including cookies, creams, and frankfurters and sausages. Furthermore, organogel technology can be used for the controlled or delayed release of nutraceuticals and pharmaceuticals. With the development of food grade organogelators, this will allow for the use of oleogels in a large variety of food and pharmaceutical applications.

Differential scanning microcalorimetry coupled to Synchrotron small angle X-ray scattering (SAXS) was used to characterize the mesomorphic phases of monostearin — a series of dispersions of monostearin and stearic acid (95:5 w/w) in alkaline water were prepared in the range 5−90% (w/w). Samples were subjected to both melting and cooling regimes from 45 to 81 at 2 °C/min in a Microcalix machine (an X-ray sample chamber with microcalorimetry capabilities), while X-ray spectra and the microcalorimetric trace were being collected simultaneously. Using these two techniques, two-dimensional phase diagrams of the mesomorphic phases (lyotropic and thermotropic liquid crystalline phases as well as the crystalline, hydrated gel phases) of monostearin was created, one for heating and one for cooling, and the typical X-ray diffraction pattern for each of the phases was identified. Polarized light microscopy was also used in an attempt to differentiate and identify the mesomorphic phases. Furthermore, the largest d-sp...

Ethylcellulose (EC) is the only known food-grade polymer able to structure edible oils. The gelation process and gel properties are similar to those of polymer hydrogels, the main difference being the nature of the solvent. The present study examines the influence of solvent quality on the large deformation mechanical behavior of EC oleogels. Two alternative strategies for manipulating the mechanical response of these gels were evaluated; manipulating the bulk solvent polarity and the addition of surface active small molecules. Gel strength was positively correlated to solvent polarity when blending soybean oil with either mineral oil or castor oil. This behavior was attributed to the ability of the polar entities present in the oil phase to interact with the EC gel network. The addition of the small molecules oleic acid and oleyl alcohol resulted in a substantial enhancement in gel strength up to 10wt% addition, followed by a gradual decrease with increasing proportions. Binding interactions between EC and these molecules were successfully modeled using a Langmuir adsorption isotherm below 10wt% addition. Furthermore, the thermal behavior of stearic acid and stearyl alcohol also indicated a direct interaction between these molecules and the EC network. Differences in the mechanical behavior of gels prepared using refined, bleached, and deodorized canola or soybean oils, and those made with cold-pressed flaxseed oil could be attributed to both oil polarity, and the presence of minor components (free fatty acids). Shorter pulsed NMR T2 relaxation times were observed for stronger gels due to the more restricted mobility of the solvent when interacting with the polymer. This work has demonstrated the strong influence of the solvent composition on the mechanical properties of EC oleogels, which will allow for the tailoring of mechanical properties for various applications.

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.

Publisher Summary It becomes more evident than ever that novel technologies need to be implemented when attempting to curb the associated epidemics and to address the resultant gigantic food manufacturing problem. To fulfill these new legislative requirements, the food industry must vigorously investigate alternatives to traditional Triacylglyceride (TAG) structuring. TAGs provide structure in numerous food products including ice cream, cheese, butter, lard, etc. Unfortunately, it is the trans and saturated lipids that provide the structure and solid-like properties of these foods. Although the structure they confer on products is desirable, and indeed required in many products, both types of fatty acids have been shown to negatively influence human health. To create a “healthy”, functional fat, the health advantageous characteristics of mono unsaturated and polyunsaturated fats needs to be utilized. This chapter examines some strategies for replacing colloidal fat crystal networks comprised of trans and saturated fats. These strategies include small-molecule organogels of unsaturated oils, structured oil-in-water emulsions, and polymer gels. The chapter describes the novel structuring mechanisms and presents some of the most promising strategies for structuring liquid oils to create a semisolid structure with the functionality of fats but with the nutritional profile of liquid oil—low in saturates, devoid of trans fatty acids, and possibly containing some nutritionally beneficial fatty acids. Structured emulsions, SAFINs, high-stearic acid fats, and polymer organogels will be a part of the solution to the problem of improving on the nutritional quality of the manufactured food products in consideration of sensory quality and price.

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.