Characterization of Aroma-Active Compounds of Pu-erh Tea by Headspace Solid-Phase Microextraction (HS-SPME) and Simultaneous Distillation-Extraction (SDE) Coupled with GC-Olfactometry and GC-MS

Abstract

Aroma volatiles from ripened and raw pu-erh tea were extracted by headspace solid-phase microextraction (HS-SPME) and simultaneous distillation-extraction (SDE). They were then characterized and identified using gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). The conditions of HS-SPME including fiber selections and sampling condition optimization have been previously investigated. With the two methods, 39 and 33 aroma-active compounds were detected and characterized in ripened and raw pu-erh tea samples, respectively. The aroma-active compounds with similar sensory descriptors were grouped into the same category, and the sum of individual aroma intensity values within each category showed that the floral aroma (33.01 %), stale/musty aroma (25.24 %), and woody aroma (11.17 %) were the major aroma categories in ripened pu-erh tea. Alcohols (floral aroma notes), methoxyphenolic compounds (stale/musty aroma notes), and ketones (woody or floral aroma notes) play a vital role in the special flavor of ripened pu-erh tea. In raw pu-erh tea, the floral aroma (38.62 %) and fruity aroma (16.55 %) were the major aroma categories. These aromas were closely related to the characteristics of raw pu-erh tea aroma and its sensory perception.