Rancidity of Soybean Oil
Oils and fats, and foods containing oils and fats, can become rancid during long-term storage, resulting in changes in color and taste. This is due to oxidation reactions with the oxygen in the air. The stability of oils and fats can be evaluated by measuring the oxidation reaction with a thermogravimeter. The effectiveness of antioxidants can be measured by determining the time until the start of the reaction (break time) at constant temperature.
The logarithm of the break time from the TGA measurements was plotted against the reciprocal of the temperature. The activation energy ΔE was determined from the gradient ΔE/R. The smaller the activation energy ΔE, the more readily the oil becomes rancid.
Simultaneous Thermogravimetric and Differential Thermal Analyzer
This DTA-TG instrument features plug-in high-sensitivity thermocouples and a differential top-loading balance with a Roberval mechanism to suppress balance sensitivity fluctuations due to discrepancies in the sample mounting position. Measures up to a 1 g sample, and achieves enhanced DTA sensitivity at high temperatures.