Effect of emulsifier type on physicochemical properties of water-in-oil emulsions for confectionery applications

In a first step of designing tailored confectionery masses using water-in-oil emulsions, a parameter screening on emulsion rheology and stability was carried out. The experimental set-up included cocoa butter as continuous phase and the variation of the disperse phase (water, or 50% sucrose in water), two volume fraction levels and the type of emulsifier (lecithin, polyglycerol polyricinoleate (PGPR), ammonium phosphatide (YN) and blends of lecithin or YN with PGPR). Emulsions were characterised by microscopy, laser diffraction, analytical centrifugation and shear rheology. Results show multimodal droplet size distributions in lecithin- or YN-stabilised emulsions, and droplets which tend to form aggregates and an internal network responsible for shear thinning. PGPR emulsions are characterised by monomodal droplet size distributions and smaller droplets without networking tendency. They exhibit Newtonian flow behaviour and a much higher stability against phase separation. In emulsifier blends, PGPR is mainly responsible for the modulation of physical properties of the emulsions.