The Phase Behavior of γ-Oryzanol and β-Sitosterol in Edible Oil

The phase behavior of binary mixtures of gamma-oryzanol and beta-sitosterol and ternary mixtures of gamma-oryzanol and beta-sitosterol in sunflower oil was studied. Binary mixtures of gamma-oryzanol and beta-sitosterol show double-eutectic behavior. Complex phase behavior with two intermediate mixed solid phases was derived from differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) data, in which a compound that consists of gamma-oryzanol and beta-sitosterol molecules at a specific ratio can be formed. SAXS shows that the organization of gamma-oryzanol and beta-sitosterol in the mixed phases is different from the structure of tubules in ternary systems. Ternary mixtures including sunflower oil do not show a sudden structural transition from the compound to a tubule, but a gradual transition occurs as gamma-oryzanol and beta-sitosterol are diluted in edible oil. The same behavior is observed when melting binary mixtures of gamma-oryzanol and beta-sitosterol at higher temperatures. This indicates the feasibility of having an organogelling agent in dynamic exchange between solid and liquid phase, which is an essential feature of triglyceride networks.