Effect of lipid type on water-in-oil-emulsions stabilized by phosphatidylcholine-depleted lecithin and polyglycerol polyricinoleate

Water-in-oil (W/O, 30:70) emulsions were prepared with phosphatidylcholine-depleted lecithin [PC/(PI,PE) = 0.16] or polyglycerol polyricinoleate (PGPR) as emulsifying agents by means of pressure homogenization. The effect of lipid type (medium-chain triacylglycerols, sunflower, olive, butter oil, or MCT-oil/vegetable fat blends) was investigated in relation to particle size distribution, coalescence stability and the sedimentation of the water droplets. A significant correlation (p < 0.05) was observed between the interfacial pressure caused by the addition of lecithin to the pure lipids and the specific surface area of the emulsion droplets (r(s) = 0.700), and between the viscosity of the lipids used as the continuous phase (reflecting the fatty acid composition) and the specific surface area of the emulsion droplets (r(s) = 0.8459) on the other hand. Blends of vegetable fat and MCT-oil led to reduced coalescence stability due to the attachment of fat crystals to the emulsion droplets. Lecithin-stabilized W/O emulsions showed significantly higher viscosities compared to those stabilized with PGPR. It was possible to adjust the rheological properties of lecithin-stabilized emulsions by varying the lipid phase.