Abstract: The thermal stability decomposition kinetics and shelflife of hydroxytyrosol were studied at different heating rates (β=5, 10, 20, 40 K/min). Thermal decomposing curves were obtained in the nitrogen atmosphere by TG analysis. Five thermal analysis kinetic methods of multi-heating rate methods(Kissinger, Friedman, Flynn-Wall-Ozawa) and single heating rate methods (Coats-Redfern and Achar) were used to speculate the probable mechanism of thermal decomposing reaction and the kinetic parameters including activation energy E_a and pre-exponential factor A. The shelflife of hydroxytyrosol at room temperature (25℃) was calculated by the kinetic parameters. The TG curve showed the decomposition of hydroxytyrosol was finished by one step, and the temperature of 260-409℃ was the main thermal decomposition stage at the heating rate of 10 K/min. With the increase of temperature, the steep and obvious weight loss occurred rapidly in the TG analysis. The DTG curve presented as negative value and decreased rapidly with the maximum loss ratio of -12.91%/min at 305.2℃. With the increase of the heating rate, thermal decomposing temperature of hydroxytyrosol rose, the thermal decomposing curves moved toward high temperature slightly and the decomposition showed hysteresis phenomenon. The probable kinetic mechanisms of thermal decomposition were one-dimensional diffusion. The average apparent activation energy (E_a) was 122.40 kJ/mol and pre-exponential factor (A) was 3.37×10¹⁰ min^-1. The theoretical shelflife of hydroxytyrosol at room temperature was about 4-5 years in the nitrogen atmosphere.

Key words: hydroxytyrosol, thermal analysis, thermogravimatry, thermal decomposition kinetics, shelflife