13 research outputs found
The Influence of Concentration and Temperature on the Formation of Îł-Oryzanolâ+âÎČ-Sitosterol Tubules in Edible Oil Organogels
The gelation process of mixtures of Îł-oryzanol and sitosterol structurants in sunflower oil was studied using light scattering, rheology, and micro-scanning calorimetry (Micro-DSC). The relation between temperature and the critical aggregation concentration (CAC) of tubule formation of Îł-oryzanol and sitosterol was determined using these techniques. The temperature dependence of the CAC was used to estimate the binding energy and enthalpic and entropic contribution to the tubular formation process. The binding energy calculated at the corresponding temperatures and CACs were relatively low, in order of 2Â RT (4.5Â kJÂ molâ1), which is in accord with the reversibility of the tubular formation process. The formation of the tubules was associated with negative (exothermic) enthalpy change (ÎH0) compared with positive entropy term (âT ÎS0 >0), indicating that the aggregation into tubules is an enthalpy-driven process. The oryzanolâsitosterol ratio affected the aggregation process; solutions with ratio of (60 oryzanolâ40 sitosterol) started aggregation at higher temperature compared with other ratios