Application of Chromatographic and Thermal Methods to Study Fatty Acids Composition and Positional Distribution, Oxidation Kinetic Parameters and Melting Profile as Important Factors Characterizing Amaranth and Quinoa Oils

Abstract

Amaranth and quinoa are classed as pseudocereals that do not belong to the grass family, meaning they are not technically a grain. Both of them are seeds with tremendous nutritional value; compared to other cereals, they contain much more fat. The aim of the study was to present the parameters characterizing thermal properties of amaranth and quinoa oils, such as: oxidation induction time, oxidation kinetic parameters, and melting profile. In isolated oils, the peroxide value, oxidative stability by the Rancimat test (in 120 °C) and the pressure differential scanning calorimetry (PDSC) method (at 100, 110, 120, 130, 140 °C), fatty acids composition, and their distribution between the triacylglycerol positions were determined. The kinetic parameters of the oxidation process (activation energy, pre-exponential factor, and reaction rate constants) were calculated using the Ozawa–Flynn–Wall method and the Arrhenius equation. To measure the melting profile, the differential scanning calorimetry (DSC) method was used. Both types of seeds are a good source of unsaturated fatty acids. Induction time of oxidation suggests that amaranth oil may have better resistance to oxidation than quinoa oil. The melting characteristics of the oils show the presence of low-melting triacylglycerol fractions, mainly containing unsaturated fatty acids, which means that a small amount of energy is required to melt the fats.

Characterization of Beeswax and Rice Bran Wax Oleogels Based on Different Types of Vegetable Oils and Their Impact on Wheat Flour Dough Technological Behavior during Bun Making

“…During the second heating and cooling profile, several endothermic and exothermic peaks were observed for the thermograms of the oleogel samples. Firstly, all the oleogels had a melting peak in the range between −40 and 0 • C, which was consistent with the endothermic peak that was recorded for the oil samples; this endothermic peak was also reported by other authors that studied the thermal behavior of vegetable oils [31,32] and was mostly related to the high content of low-melting triacylglycerols and the high proportion of mono-and polyunsaturated fatty acids that are the main components of the vegetable oils used to prepare oleogels [33]. The second melting peak was similar to the peak recorded in the first heating profile; however, the melting enthalpy was lower when compared with the first heating, thereby suggesting that after the first heating and cooling profile, the structure of the oleogel changed.…”

Physicochemical and Morphological Study of the Saccharomyces cerevisiae Cell-Based Microcapsules with Novel Cold-Pressed Oil Blends

“…Triacylglycerols containing unsaturated fatty acids in their structure are characterized by negative maximum peak temperatures (Figure 5). It proves the content of MUFA and PUFA in triacylglycerols of the tested oils [55]. In Figure 5, no endothermic peaks were observed; the maximum temperature would have had positive temperature values.…”