Rheological properties of emulsion templated oleogels based on xanthan gum and different structuring agents
M. Espert, M.J. Hernández, T. Sanz, Ana Salvador
Abstract
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.