Aroma characterisation of Pu-erh tea using headspace-solid phase microextraction combined with GC/MS and GC–olfactometry

Volatile compounds from Pu-erh tea were extracted using a headspace-solid phase microextraction (HS-SPME), and analysed with a gas chromatography–mass spectrometry (GC–MS) and a gas chromatography olfactometry (GC–O). Results showed that a total of 66 major volatile compounds were identified by GC–MS analysis; among them, methoxy-phenolic compounds (33.58%), alcohols (23.01%) and hydrocarbons (11.62%) were the major chemical classes. It was found that 1,2,3-trimethoxybenzene (17.16%) was the most abundant aroma components, followed by α-terpineol (5.68%), 1,2-dimethoxybenzene (4.64%) and linalool oxide II (4.29%) in order. Twenty-nine odour active compounds were perceived by GC–O analysis. Further investigation showed that 1,2-dimethoxybenzene, 1,2,3-trimethoxybenzene, 1,2,3-trimethoxy-5-methylbenzene, 4-ethyl-1,2-dimethoxy-benzene, β-ionone, β-linalool, linalool oxides, decanal, etc. were responsible for the special flavour in Pu-erh tea. It seems that the methoxy-phenolic compounds and alcohols play a vital role in the special flavour of Pu-erh tea.