Study on Aroma Components in Different Types of Dark Tea Based on HS-SPME-GC-MS

Headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and sensory evaluation were used to investigate the aroma characteristics of different dark tea products (Fu brick tea, Dark brick tea, Tibetan tea, Liupao tea, and Tianjian dark tea). Sensory evaluation results showed that the aroma characteristics of the five dark tea samples differed remarkably. Fungal and stale aromas were the major aroma profiles of Fu brick tea. Results showed that, Liupao tea had obvious persistent areca-like and stale aromas, Tibetan tea had a persistent stale aroma, and Dark brick tea exhibited a pure aroma feature. Furthermore, Tianjian dark tea showed a persistent smoked aroma. The following rank order of the score of the sensory evaluation in the five dark teas was observed: Tibetan tea (91.35) > Fu brick tea (90.15) > Dark brick tea (89.05) > Liupao tea (88.85) > Tianjian dark tea (86.33). A total of 56 volatile compounds were identified in the five dark teas. The composition and content of aroma components varied significantly among the different dark teas. Contents of the volatile compounds in the five dark teas with the following rank order: Fu brick tea (6355.30 μg/L) > Tibetan tea (5858.73 μg/L) > Dark brick tea (5789.71 μg/L) > Tianjian dark tea (4801.37 μg/L) > Liupao tea (3740.14 μg/L). Multivariate statistical analysis and odor activity values analyses showed that 1,2,3-trimethoxybenzene was the characteristic volatile component of the stale aroma of Tibetan tea. (E,E)-2, 4-decadienal, (E,E)-2, 4-nonadienal, citral I, citral II, hexanal, and methyl salicylate contributed to the fungal aroma of Fu brick tea, while 1,2,3-trimethoxybenzene was the key contributor to the stale aroma of Fu brick tea. In Liupao tea, (+)-cedrol was a major contributor to the areca-like aroma. (E,E)-2, 4-decadienal, (E,E)-2, 4-nonadienal, hexanal, and phytol were the main contributors to the pine-smoked aroma of Tianjian dark tea. The pure aroma of Dark brick tea was formed by the comprehensive action of many volatile components, including benzene ethanol, neroltertiary alcohol II, and oxidized linalool I. This study would provide a statistical basis for exploring the aroma quality of different types of dark teas.