Robust sugar alcohol with lecithin functionalities for sustainable gelation of edible oils

Abstract

Edible oleogels are of interest to many researchers in the food industry. However, the applications of oleogels in foods are limited owing to the demand for food-grade and low-cost gelators. In this study, we investigated a facile and reliable route for the formation of oleogels using lecithin and D-sorbitol as gelators, which are food-grade and commercially available. Grapeseed, olive, rice bran, and sesame oils are used as edible oils and all of which gel at a certain molar ratio of lecithin (40 mM) and D-sorbitol (42–54 mM), wherein the samples do not flow downward in the inverted vials and the formed oleogels are analyzed. The rheological properties of the samples, such as zero-shear viscosity (∼20 Pa.s to infinite viscosity), viscous modulus, and elastic modulus (70–110 Pa) under diverse conditions (i.e., shear-stress and temperature), were explored in detail by steady-shear and dynamic rheology. The mechanism of gel formation was also studied using small-angle X-ray scattering (SAXS) technique, which revealed that the gel was formed by the entanglement of the reverse cylindrical micelles (slop of I vs q: ∼1) induced by the hydrogen bonds between lecithin and D-sorbitol. Furthermore, the hydrogen bonds were confirmed with the Fourier transform infrared spectroscopy (FTIR), in which the absorbance bands of phosphate (red-shift) and carbonyl groups (blue-shift) of lecithin are shifted upon addition of D-sorbitol. Finally, this method to create oleogels of diverse edible oils using lecithin/D-sorbitol mixtures is simple and reproducible; thus, mass production of oleogels for marketable consumer products is expected to be achieved.