Effects of drying process of yuanzhi (Radix Palygalae) on its bioactive ingredients.

Objective: To study the effects of the drying processing in terms operational parameters on the bioactive constituents of six Yuanzhi (Radix Palygalae) samples across China.
Methods: Six Yuanzhi (Radix Palygalae) samples were investigated using thermogravimetry analysis. The heating courses were set in two ways: the temperature-programmed process from room temperature to 150 degrees C, and the constant-temperature course at 50 degrees C, 70 degrees C and 90 degrees C.
Results: The peak temperature of six Yuanzhi (Radix Palygalae) samples ranged from 78 degrees C to 88 degrees C. The mass loss rate of Yuanzhi (Radix Palygalae) alcohol-soluble extract was significantly increased when heated at 90 degrees C. Four types of bioactive ingredients were detected in volatile oils of Yuanzhi (Radix Palygalae) sample from Shanxi province by Gas Chromatography-mass spectrometry analysis. Fourier Transform Infrared Spectroscopy results showed that the drying temperature exerted a great influence on types and amount of ingredients of Yuanzhi (Radix Palygalae). The kinetic study showed that the constant-temperature drying process of Yuanzhi Radix Palygalae) samples could be well described by the Page Model, especially for the drying process at 50 degrees C, in which R2 and SD values were more than 0.98 and less than 0.04, respectively. The drying constant k of three Yuanzhi (Radix Palygalae) samples from Shanxi, Gansu and Shaanxi provinces in China was corresponding to the Arrhenius equation, and their activation energies were 28.07, 25.38 and 21.48 kJ/mol, respectively.
Conclusion: The drying process of Yuanzhi (Radix Palygalae) was very important for bioactive ingredients improvement in Yuanzhi (Radix Palygalae). Temperature was a thermodynamic property significantly affecting the process.