Emulsification and adsorption properties of hydrophobically modified potato and barley starch

In this paper, we studied the adsorption at emulsion droplets of potato starch, which was hydrophobically modified with octenyl succinate anhydride (OSA), a surface active macromolecule containing ultrahigh molar mass components. The results show that the substance works as an efficient emulsifier and that it can in some cases generate high surface loads (10 mg/m2). The results can be explained as an interplay between kinetic factors during the formation of the emulsion and the physical-chemical properties of the hydrophobically modified starch, such as the degree of substitution, molar mass, and radius. In turbulent flow fields, such as in a high-pressure homogenizer, the mass transport to the interface favors the adsorption of larger molecules as they are transported more rapidly to the interface. The larger molecules are also likely to have a higher substituent density and adsorption energy than smaller ones. This in turn is likely to give high surface loads and strengthen the effect of kinetic adsorption factors, as the large molecules will be overrepresented at the surface.