17G-26 |
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M. EISENMENGER and N. T. Dunford. Dept. of Plant & Soil Sciences, Oklahoma State Univ., 103 FAPC, Stillwater, OK 74078 Wheat germ processing presents challenges due to its high content of polyunsaturated fatty acids and bioactive compounds. These compounds are prone to oxidation and degradation under the conditions used for conventional edible oil extraction and refining methods. Thermal analysis techniques, such as Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) have been used to characterize physical and chemical properties of edible oils. In this study four wheat germ oil samples were analyzed using a computer controlled TGA (Mettler Toledo TGA/SDTA851e) instrument. Two refined and one crude wheat germ oil samples were obtained directly from a commercial processor. These samples were extracted with hexane from full fat wheat germ. A supercritical carbon dioxide extracted wheat germ oil sample was also analyzed. Both isothermal and non-isothermal TGA tests were carried out at the temperature range of 25-800oC under air and nitrogen. Non-isothermal tests were carried out at 2, 5, 10 and 20oC/min heating rates. The sample size was 4-5 mg. Thermal stability of the oil samples were evaluated based on the TGA, DTG (Derivative gravimetry) and SDTA (Single Differential Thermal Analysis) curves. Thermal decomposition kinetic parameters (reaction order and activation energy) of each oil sample were calculated from Arrhenius equation. The experimental results indicate that TGA is a simple and fast method to evaluate thermal stability and degradation properties of edible oils.
Session 17G, Food Engineering: Physical, chemical and electrical properties
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