Comparison of volatile compounds among different types of Tieguanyin oolong tea using DHI-GC-MS

Depending on the manufacturing process, Tieguanyin tea (TGY) is classified into three main groups, light flavor type (LFT), heavy flavor type (HFT), and stale flavor type (SFT). However, the compositions and contents of volatile compounds among TGY types were still unclear. This study aimed to develop an efficient method for the nonselective determination of volatile compounds in teas via direct-headspace injection coupled with gas chromatography mass spectrometry (DHI-GC-MS), and to perform a comprehensive comparison among these teas. One hundred and twelve volatile compounds belonging to 9 classes were identified. Among them, 33 common volatiles from 4 categories (aldehydes, alcohols, ketones, and acids) were the dominant volatiles and accounted for 71.5%, 73.0%, and 71.8% of the total amount in LFT, HFT, and SFT, respectively. E-Nerolidol, ethanol, acetic acid, and some volatiles with five and six-carbon chains were the key chemicals to distinguish three different TGY teas. With PLS-DA analysis, distinct differences among different groups were observed. The results generated from this study may offer valuable insights for better grading of TGY teas.