Abstract: To better evaluate the thermal stability of spices and enhance their practical value, a uniform evaluation method for the thermal stability of spices was established by combining thermogravimetric analysis-sample storage interface-gas chromatography-mass spectrometry (TGA-IST-GC-MS) with TGA and GC-MS. First, the method used TGA to obtain the optimal injection temperature of spices based on their volatility characteristics. Then, GC-MS and TGA-GC-MS chromatograms were obtained under different systems. By comparing the two chromatograms, the stability, cracking degree, and fragmentation degree were calculated as three important thermal stability indicators of spices. Finally, the aroma changes of spices before and after heating were investigated based on their thermal stability. The results indicated that using the peak temperature for maximum mass loss rate during spice volatilization as the optimal injection temperature for TGA-IST-GC-MS, the developed method had high response intensity and good repeatability. Comparing the GC-MS and TGA-GC-MS chromatograms, the influence of spice matrix background was effectively reduced, which improved the accuracy of the method, making it suitable for both single-component spices and multi-component natural spices. Based on the three indicators of thermal stability, it could further obtain the cracking intensity and the amount of new cracking products during the heating of spices, which is of great practical and guiding significance for aroma evaluation.

Key words: thermogravimetric analysis-sample storage interface-gas chromatography-mass spectrometry; spice; thermal stability; cracking products; aroma evaluation