COMPOSITION OF FATTY ACIDS IN VEGETABLE OILS OBTAINED BY GAS CHROMATOGRAPHY AND ITS CORRELATION WITH THERMAL, RHEOLOGICAL, SPECTROSCOPIC AND OTHER PHYSICO-CHEMICAL PROPERTIES
Vegetable oils, quality parameters, thermogravimetry, GC-MS, rheological study, physicochemical analysis, fatty acid profile
This work determined the acidity index (IA), saponification (IS), peroxide (IP), iodine (II), refraction (IR), relative density (d), viscosity (ƞ), composition and acid distribution (OR), cacay (OC), quinoa (OQ), green coffee (OCV), jamelão (OJ), and moringa extracted from the fruit of the annatto (OR), according to the Association of Official Analytical Chemists of seeds and leaves and flowers, respectively WHO and OMFF. It performed the thermal characterization using thermogravimetry and calorimetry. The volatiles released during their thermal decomposition by TG-FTIR and a rheological study were analyzed. From the rheological study, the following order OR> OC> OJ> OCV> OMS> OQ> OMFF was obtained for activation energy (Ea). From the TG / DTG / DSC curves obtained, it was verified that each analyzed oil had peculiarities in its thermal decomposition, the order of stability proposed through TG / DTG is OQ> OMFF> OCV> OMS> OJ> OC> OU. From the infrared spectra it was possible to observe the evolution of the volatiles during the thermal decomposition, in the atmospheres of synthetic air and N2, of the different oils. It has been found that each oil has different intensities in the thermal decomposition products. It was observed that the products of the decomposition of the studied oils presented the same profile during their thermal decompositions, it is concluded that there is a pattern in the thermal decomposition of these oils with products of similar decomposition. Chromatograms indicated the presence of 13 fatty acids with linoleic acid (C18: 2n6c) being the most abundant fatty acid in all samples. The OMFF sample presented higher content of unsaturated fatty acids while the OJ sample presented higher content of saturated fatty acids.