Correlation between fatty acid composition of oils and phenomenon of polymorphism

We studied the fatty acid composition of some oils and established its effect on the processes of melting and crystallization. The melting and crystallization processes were investigated by differential scanning calorimetry (DSC). To study the correlation between phase transitions and fatty acid composition, the following vegetable oils were used: sesame, corn, soybean, sunflower, coconut and jojoba. The first four oils have different fatty acid content, polyunsaturated fatty acids account for more than 50%. The presence of three phase transformations and inversion of the melting and crystallization peaks are observed in the DSC diagrams for these four oils. Coconut oil contains 93.39% of saturated fatty acids and two peaks of phase transformations are observed in the DSC diagram of melting and crystallization processes. This can be explained by the fact that the total amount of fatty acids C12:0 and C14:0 is 67.14%. Jojoba oil contains 93.89% of monounsaturated fatty acids, and 62.20% of them are presented by gondoic fatty acid (C20:1). The DSC diagram of jojoba oil exhibits one characteristic peak of phase transformation. The obtained results allow establishing a certain correlation between the parameters of fatty acid composition and DSC diagrams.