Structuring of water-in-oil emulsions using controlled aggregation of polysaccharide in aqueous phases

The influence of high methoxy pectin, kappa-carrageenan (kC) and starch on the rheological and microstructural properties of structured Water-in-Oil emulsions was examined. An acidic aqueous phase (pH 3.5) was prepared by dispersing 2 wt % of polysaccharides in buffer solution (10 mM Citrate, 100 mM NaCl), while the oil phase consisted of lipophilic nonionic surfactant (8 wt % polyglycerol polyricinoleate) in Soybean oil. These phases were emulsified to create 40 wt % Water-in-Oil emulsions, and were either characterized before or after heat treatment at 90 °C for 30 min. It was observed that the shear viscosity and shear modulus of heated emulsions were higher than for unheated systems, which can be attributed to heating induced gelation process in polysaccharide molecules primarily, as well as influence on the overall rheology of W/O emulsions. The shear viscosity and shear modulus of kC in aqueous solutions, as well as in emulsions, were higher than the other polysaccharide systems, which may be due to formation of larger junction zones in kc emulsions. This work's insights may contribute in fabrication of reduced fat margarine and spreads.