Combined chromatography and mass spectrometry for the molecular characterization of food emulsifiers

Food emulsifiers are widely used to stabilise water-fat emulsions such as mayonnaise and dressings. They are prepared by oligomerisation of a poly-alcohol (as e.g. glycerol or citric acid) followed by a reaction with fatty acids. In order to gain insight in the chemical composition of different emulsifiers, a range of chromatographic methods including gas chromatography, size exclusion chromatography, normal phase- and reversed phase liquid chromatography either or not in combination with mass spectrometry was deployed. The different methods turned out to be highly complementary. By combining the information from different methods the polar head group and the fatty acid part of the emulsifier can be characterised in detail. Mass spectrometry is indispensable for establishing the number of polar molecules in the head group as well as for establishing the correct combinations of fatty acids in one molecule. Ten commercial emulsifiers were described at the level of number and type of polar groups and fatty acids present.