Cholesterol thermodynamic behaviour in mixtures with medium chain fatty acids and vegetable oils composed of them

Abstract

The fatty acid profile of fats and oils are always the main target of the discussions on how cholesterol body levels could be increased or decreased by the feed habits. Specially, medium chain saturated fatty acids and palmitic acid are related to the blood LDL increase, promoting cardiovascular diseases. Otherwise, the same fatty acids are also related to a better digestion, increasing the popularity of some oils, such as coconut oil. This work was then aimed to contribute with this discussion in a thermodynamic point of view. Mixtures with cholesterol and these fatty acids (caprylic, capric, myristic and palmitic acids) were formulated in several concentrations and their crystallization and melting profiles analysed. Solid-liquid equilibrium phase diagrams were built and evaluated by using classical thermodynamic models. Results showed that lower fatty acids were significantly able to modify the cholesterol crystal structure, forming solid solutions. The performance of the thermodynamic models was mild good. The UNIFAC model showed limitations in representing the cholesterol structure, as expected, with highlights that its literature's parameter databank should be improved, considering the complexity of molecules such as cholesterol. Additionally, coconut and palm oils were also evaluated in mixtures with cholesterol, showing that despite its high melting temperature and molecular complexity, cholesterol could be solubilized in such oils. The palm oil, specially, presented liquid crystalline structures when mixed with cholesterol. All these phenomena observed could probably affects cholesterol solubility in lipidic media, being a factor that could influence their absorption in the gastrointestinal tract.