The structural properties of oils and fats are of interest for different sectors of the technological and scientific community. The mineral oil industry is interested in methods preventing gelation of (crude) oil in pipe lines [1, 2]. On the other hand novel materials based on structured oil matrices are desired as well in food technology [3-5] for structured products as in pharmaceutical technology for controlled release properties  or in material science for tuning hardness of materials. Here we present the structural properties of organogels made from mixtures of stearic acid (Ac) and 1-octadecanol (Ol) in vegetable oil and a rheological evaluation of the resulting texture. Oscillating strain measurements are performed as a function of the temperature on the ternary system Ac/Ol/liquid vegetable oil. The total mass concentration of Ac/Ol was kept constant at 5 wt% in the ternary systems. Rheology experiments reveal a strong increase of the elastic modulus at temperatures under 30oC. It is shown that the 1 to 2 mixture of Ac/Ol has an elastic modulus that is significantly larger than that of the other ternary samples. Using microscopy it is found that the shape of the crystals in the samples depends strongly on the composition of the mixture. The cause of the observed behavior of the elastic modulus lies in the crystal morphology due to the molecular structure of the self assembled lipid crystals. X-ray diffraction at small and wide angles revealed that at a 2/1 ratio a compound crystal is formed. The resulting crystal form is very likely to the ß modification of the StStSt. However no esterification could be noticed. The understanding of this synergetic effect in a very narrow concentration range of 1-octadecanol, and stearic acid in the organogels provides the possibility to tune the hardness of the lipid matrix.
|Title of host publication||Abstracts of the 24th European Crystallographic Meeting, Marrakech, Morocco, 22 - 27 August, 2007|
|Publication status||Published - 2007|
|Event||24th European Crystallographic Meeting, Marrakech - |
Duration: 22 Aug 2007 → 27 Aug 2007
|Conference||24th European Crystallographic Meeting, Marrakech|
|Period||22/08/07 → 27/08/07|