Palm and olive oils differentially alter phase structure and repulsive interaction between bilayers of gel phase formed by mixed monoglycerides

The influence of olive and palm oils on the gel phase formed by mixed saturated and unsaturated monoglycerides in the absence and presence of water has been examined by X-ray diffraction. Unexpectedly, whilst olive oil had little interaction with the gel phase, some palm oil was incorporated into the gel phase increasing its stability with much lower swelling in water. We have also made water vapour pressure measurements to investigate the interaction forces between lipid bilayers. Palm oil increased vapour pressure significantly compared to G50 (mixed saturated and unsaturated monoglycerides), more than what was observed for olive oil. It is generally accepted that the interaction forces are dominated by hydration, one description employs an exponentially decaying force transmitted through water [water-structure], while the second invokes lipid/water H-binding. Both can describe the experimental data, but because the water-structure model employs non-physical parameters the second mechanism is preferred. The findings provide novel insights and implications on the functionality and stability of glycerolipids in manufacturing next generation effective medicines, foods and cosmetics.