(de)stabilize an oil-in-water emulsion at neutral or acidic pH? A review

This paper reviews the effects of the addition of flaxseed gum on the physicochemical properties of whey protein-stabilized, oil-in-water emulsions at neutral and acidic pH as investigated by light scattering and rheology under dilute and concentrated conditions. At pH 7.0, measurements performed in the dilute system showed no changes in charge or size of the droplets however, in the concentrated case, the amount of gum added had a noticeable effect on the final state of the system. At low gum concentration, no evident changes were recorded. At middle concentration of flaxseed, rapid phase separation was observed while at the highest amounts of gum used in this study, high background viscosity delayed the destabilization process. At pH 3.5, the opposite charge between the polysaccharide (negative) and the whey protein isolate, WPI (positive) led to electrostatic interactions between the species. In this case, both measurements, under dilute and concentrated states, yielded differences as a function of gum amount. At low and mid-concentrations, gum adsorption onto the interface resulted in larger particle size measurements with lower z-potential charge. At high enough concentration, bridging flocculation took place. When sufficient amount of flaxseed gum was present, gel-like properties were observed.