The Colloidal Behavior of Pectin Containing Water in Oil Emulsions as a Function of Emulsifier Concentration

The aim of this research was to investigate the effect of polyglycerol polyricinoleate (PGPR) on the stability and colloidal behavior of W/O emulsions, with or without pectin present in the water phase. Stable emulsions containing 30 % water were obtained using 2 % PGPR. When diluted, the size of the droplets formed measured by dynamic light scattering, was inversely proportional with the concentration of PGPR; however, these results were not in agreement with rheology and diffusing wave spectroscopy measurements at higher concentrations of PGPR (> 4 %). The discrepancy suggested that compositional changes in inner water phase affected the w/o interface and the physico chemical properties of the emulsions. It was hypothesized that in the presence of pectin less PGPR was needed to form the water droplets. In the absence of pectin, PGPR emulsions were less turbid than when pectin was present in the water phase. In all cases, when the emulsions were further diluted with oil, they showed a hard sphere behavior. These results highlight the importance of studying water in oil emulsions using bulk rheology and light scattering without dilution, as it is possible to better understand differences in their colloidal properties.