Molecular self-assembly in the development of a new generation of edible fats

By Jorge F. Toro-Vazquez, PhD

Universidad Autónoma de San Luis Potosí

Tuesday October 27th, 2020 at 11:00 am (Mexico City, MX; 17:00 UTC)

Traditionally, we associate the development of gels with polymeric compounds like casein, starch, collagen, carrageenan and the like. The hydrophilic character of these polymeric gelators renders them capable of holding large amounts of water within a three-dimensional fiber network of the polymer. In contrast, in organogels, also known as molecular gels, the gelators are mainly low molecular weight compounds that self-assemble in organic solvents (i.e., vegetable oils), developing supramolecular structures stabilized through short-range, non-covalent interactions. The development of organogels has emerged as a new and exciting field of lipid research from fundamental to an applied perspective. The possibility of using vegetable oils to develop organogels (i.e., oleogels) would allow a significant reduction of saturated fatty acids and the elimination of trans-fatty acids from the food systems, and subsequently from the consumer's diet. The development of oleogels is easily achieved by heating a dispersion of a low molecular-mass organic gelator (LMOG) in the vegetable oil until achieving its full solubility, and then cooling the system below the LMOG's solubility limit temperature in the oil. Through this process the gelator molecules go through spontaneous self-assembly, developing a viscoelastic, thermoreversible, bicontinuous supramolecular material that entraps the oil within a three-dimensional crystal structure. This three-dimensional network, stabilized mainly through nonspecific short-range forces (i.e., London dispersion forces and van der Waals forces), holds micro domains of the liquid in a non-flowing state mainly through surface tension. In this webimar I will discuss the major physical and chemical variables involved in the development of oleogels, the relationship between the molecular structure of selected LMOG and its relationship with some physical properties of oleogels. Additionally, I will present experimental evidence that shows the combined effect of shear and cooling rates to engineer the rheological properties of oleogels, particularly those developed with vegetable waxes. Several vegetable waxes (i.e., candelilla wax, rice hull wax, sunflower wax) are capable of structuring large volumes of vegetable oils, producing edible oleogels with similar functionality to trans and saturated fats.