Rheological properties of emulsion templated oleogels based on xanthan gum and different structuring agents

Oleogel design based on emulsions using food grade polymers is a potential strategy for replacing saturated and trans fats. The aim of this paper is the characterization of sunflower oil-based oleogels structured by a non-surface-active polysaccharide, xanthan gum (XG), in combination with different structuring agents, through an emulsion template approach, which consists in the dehydration of the continuous phase of an oil/water emulsion. Four types of molecules with different origins were used: a synthetic one, polysorbate Tween 80, and other three from natural sources: a protein (whey protein, WP), a lipid (soy lecithin, SL) and a polysaccharide (locust bean gum, LBG). All the emulsions had a high shear thinning character (s = 0.45) and a weak gel behaviour (tanδ = 0.2). Only the LBG emulsions presented significant differences, with higher values of viscosity and viscoelastic moduli. The resulting oleogels showed high gel strength, exhibiting a marked elastic behaviour typical of structured solid systems (G'>G'' and tanδ = 0.06). SL oleogels stood out for presenting the lowest firmness, although internal structure seems to be similar to the rest. Regarding to stability, measurements indicated a great oil binding capacity (90% approx.) after 24 h. It is concluded that obtaining stable and solid-like oleogels with liquid oil using a hydrophilic polymer (XG) combined with different food-grade structuring agents was possible. These systems have great potential in food reformulation, especially for saturated fat substitution.