Investigation of the Thermal Decomposition Behavior of Oleuropein with Many Pharmacological Activities from Olive by Thermogravimetry

Abstract

Due to the existence of poly-hydroxyl structures, the temperature may have an effect on the thermal stability of oleuropein for its applications. In the current study, the thermal decomposition process and kinetics behavior of oleuropein from the olive resource were researched by thermogravimetric theoretical analysis methods and non-isothermal kinetics simulation. The results of thermogravimetry analysis showed the whole thermal decomposition process of oleuropein involved two stages, with 21.22% of residue. It was also revealed that high heating rates of more than 20 K min−1 led to significant thermal hysteresis and inhibited the whole thermal decomposition behavior of oleuropein. Moreover, an investigation of the thermal decomposition kinetics indicated that the non-isothermal decomposition behavior followed a D3 model during the first stage (three-dimensional diffusion, Jander equation) and a D1 model in the second stage (one-dimensional diffusion). For the first and second thermal decomposition stages, the Kissinger, Friedman, Flynn-Wall-Ozawa, and Coats–Redfern four methods were applied to determine the activation energy (E = 143.72 and 247.01 kJ mol−1) and Arrhenius preexponential factor (ln A = 26.34 and 42.45 min−1), respectively. Therefore, the study will provide good theoretical guidance for thermal stability and thermal transformation application of oleuropein. It will be suitable for low-temperature applications in the cosmetic, food supplement and pharmaceutical industries.