关键词: 六堡茶, 全二维气相色谱-飞行时间质谱, 香气成分, 香气特征

Abstract: Liubao tea is one of China’s most well-known teas with a long history of consumption, which has a unique aroma quality. The composition and relative contents of aroma components in a representative batch of Liubao tea were analyzed by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS). A total of 307 aroma components were identified from the tea samples, including 7 enols, 23 alkenes, 5 amines, 20 alkanes, 14 aldehydes, 14 olefin aldehydes, 22 ethers, 7 alcohols, 10 esters, 7 lactones, 5 allyl esters, 30 ketenes, 49 ketones, 5 phenols, 11 organic acids, 5 sulphur compounds, 20 nitrogen heterocyclic compounds, 7 oxygen heterocyclic compounds, 40 aromatic hydrocarbon compounds, 3 alkynes and 3 acid anhydrides, and 21 other compounds. The results showed that the aroma of Liubao tea was mainly composed of organic acids, aromatic hydrocarbon compounds, ethers, and aldehydes, and their relative contents were 16.55%, 13.50%, 10.92% and 10.04%, respectively. There were 54 aroma compounds accounting for less than 0.5% of the total amount of volatiles, the predominant ones being hexadecanoic acid (14.95%), benzaldehyde (3.03%), 3,7-dimethyl-1,6-octadien-3-ol, (2.19%) and (E,E)-2,4-heptadienal (2.04%). The analysis of characteristic aroma components showed that organic acids (such as hexadecanoic acid), aromatic hydrocarbon compounds (such as ethylbenzene), ethers (such as 1,2,3-trimethoxybenzene and 2-methoxy-naphthalene), aldehydes (such as benzaldehyde and 3-methyl-butanal) and ketones (such as α-ionone) may have a direct impact on the aroma quality of Liubao tea.

Key words: Liubao tea, GC × GC-TOFMS, aroma components, aroma characteristics