Separation of aroma components in Xihu Longjing tea using simultaneous distillation extraction with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

Aroma is one of the most important determinants of tea quality; thus, the precise characterization of the chemical composition of tea aroma is of significant value. In this study, aroma components of the most famous Chinese green tea, Xihu Longjing tea, were first systematically analyzed using comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC   ×   GC-TOFMS) combined with simultaneous distillation extraction (SDE). 478 volatile compounds were identified as common constituents of fifty-five Xihu Longjing tea samples based on standard mass spectra in available databases, retention times, retention indices, structured chromatograms and standards. Subsequently, the aroma qualities of Xihu Longjing tea samples were discriminated by sensory evaluation combined with multivariate analysis. The study results indicated that 37 compounds were positively correlated with aroma quality, and 65 compounds were negatively correlated with aroma quality. The above compounds with various odor characteristics were considered as the key components to affect the aroma quality of Xihu Longjing tea.