Influence of different β-glucans on the physical and rheological properties of egg yolk stabilized oil-in-water emulsions

The objective of this study was to obtain additional information on the influence of different beta-glucan preparations, i.e. curdlan (CL), barley (BG), oat (OG), and yeast (YG) beta-glucans, on the physical and theological properties of egg yolk stabilized oil-in-water emulsions containing 20% oil. The emulsion without beta-glucan (REF) was also prepared as a reference. Addition of CL and OG increased emulsion oil droplet sizes, whereas BG and YG showed no effect. Emulsion microstructures revealed that beta-glucans induced flocculation of the oil droplet in the following order: CL > BG approximate to OG > YG. Dynamic oscillatory shear tests indicated that all emulsions exhibited weak gel-like characteristics which were enhanced by beta-glucans addition as evidenced by an increase in G' and a decrease in tan delta values. Flow tests showed that beta-glucans enhanced thixotropy and yield stress of the emulsions. Stability tests demonstrated that beta-glucans addition improved creaming stability of the emulsions during storage possibly due to an increase in viscosity of the continuous phase and/or a formation of a three-dimensional droplet network. CL exhibited the most pronounced effects on the aforementioned properties of emulsions compared to the other beta-glucans tested. YG gave emulsion with higher viscoelastic properties and yield stress but lower stability than those made with BG or OG, indicating complex relationship between rheology and stability of these emulsion systems. (C) 2008 Elsevier Ltd. All rights reserved.