Effect of hydrogen bonding on water in oil emulsion properties

Abstract

The amphiphilic properties of the large majority of edible water in oil (W/O) emulsifiers are due to the presence of hydroxyl groupsd in their hydrophilic group. These cause such emulsifiers to adsorb at the W/O interface, to stabilize W/O emulsions, and to form inverse micelles in the oil phase. They also cause the formation of hydrogen-bonded complexes with nonaqueous solvents containing proton acceptor groups, e.g., with trigylceride oil. By comparing the critical micelle concentration (CMC) values of a series of such emulsifiers in hydrocarbon oil and in sunflowerseed oil with the infrared spectra of the corresponding solutions, it is shown that the higher CMC values in the latter solvent are due to hydrogen bonding between the emulsifier monomers and the solvent. Formation of such complexes is decreased if the emulsifier structure allows intramolecular hydrogen bonding. — If no hydrogen bonds with the solvent are formed, W/O emulsions are stable when the emulsifier concentration in the oil after preparing the emulsion at least equals the CMC. However, for emulsifiers having a low CMC value a large excess concentration is needed to stabilize W/O emulsions in hydrogen-bonding solvents such as sunflower seed oil.