Stability determination of soy lecithin-based emulsions by Fourier transform infrared spectroscopy

The stability of soy lecithin-stabilized emulsions was determined by Fourier transform infrared spectroscopy. Oil-in-water (o/w) emulsions were prepared with 6% (vol/vol) medium-chain triglycerides (MCT), 94% (vol/vol) water, and 4% (wt/vol) Lecigran and Lecimulthin soy lecithin. There were little or no differences between the 4% Lecigran and 4% Lecimulthin emulsions for all vibrational regions studied (OH at 3348 cm(-1), C=O at 1741 cm(-1), PO and C-O-C at 1157 cm(-1), and P-O-C at 1101 cm(-1)), but the control emulsion, without emulsifier, had increased vibrations as the emulsion separated. The weaker vibrations of the more stable emulsions were probably due to reduced:molecular interaction at the interface, However, added magnesium or calcium chloride enhanced the vibration of these groups, probably by disrupting the lecithin interaction at the emulsion interface.