Characterization, thermal properties and phase transitions of amazonian vegetable oils

Thermal profiles of buriti pulp oil ( Mauritia flexuosa Mart.), tucumã pulp and kernel oils ( Astrocarium vulgare Mart.), rubber seed oil ( Hevea brasiliensis ), passion fruit oil ( Passiflora edulis ) and ucuúba butter ( Virola surinamensis ) were analyzed by thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). Gas chromatography and calculated iodine values were performed to determine the fatty acid profile and to measure the degree of unsaturation in these oils, respectively. The TG curves showed three steps of mass loss, which can be attributed to the degradation of polyunsaturated, monounsaturated and saturated fatty acids. The DSC crystallization and melting curves are reported and depended on the fatty acid composition. Usually, oil samples with a high degree of saturation showed crystallization and melting profiles at higher temperatures than the oils with a high degree of unsaturation. The data obtained by physicochemical analysis of oil samples were analyzed by principal component analysis and hierarchical cluster analysis to increase understanding of the data set, examining the presence or absence of natural groupings between samples.