Influence of oil type on formation, structure, thermal, and physical properties of monoglyceride-based organogel

This research studied the possible relation between oil properties and structure and physical properties of saturated monoglyceride (MG)-based organogels. To this aim different oils (castor, cod liver, corn, extra virgin olive, flax-seed, peanut and sunflower oil, and mixture of medium chain triacylglycerols (MCT)) were used to prepare organogels by adding 10% w/w of monoglycerides. The fatty acid composition, viscosity, and dielectric properties of oils were measured. Then, organogels were characterized for crystallization induction time, dielectric properties, firmness, rheological behavior, thermal properties, crystal morphology by polarized light microscopy, and crystal polymorphism by synchrotron X-ray diffraction (XRD) analysis. Results acquired showed that the addition of MG in different types of oils led to the formation of organogels with different properties. In all cases, β polymorph formed in the system irrespective of oil type. Regarding oils containing long chain fatty acids, gel firmness, and other structural parameters correlated well with the dielectric constant and/or viscosity of oils: increasing oil viscosity or decreasing oil dielectric constant, firmness and rheological parameters linearly increased. On the other hand, these correlations cannot be found including in the statistical analysis castor oil or MCT, probably due to the higher ability of these oils to make dipole-dipole rotation as well as the higher solubility of MG in castor oil. Practical applications: Oil gelation (organogelation) is a relative novel strategy to convert liquid oils into structured systems that has attracted food scientists and industry managers looking for solutions to reduce saturated/trans fats, deliver bioactive molecules, and minimize oil migration in foods. Results acquired in this research highlight that the choice of oil to be structured by means of saturated monoglycerides could affect the final gel structure. These findings could be useful in the attempt to applied organogels in different food products having different physical properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.