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Journal of Tea Science ›› 2020, Vol. 40 ›› Issue (6): 771-781.doi: 10.13305/j.cnki.jts.2020.06.006

• Research Paper • Previous Articles     Next Articles

Aroma Profiling of Fresh Leaves of Oolong Tea Cultivars during White Tea Processing

CHEN Lin1, ZHANG Yinggen1, CHEN Jian1, SONG Zhenshuo1, XIANG Lihui1, YU Wenquan1,2,*, YOU Zhiming1,*   

  1. 1. Tea Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350013, China;
    2. Fujian Academy of Agricultural Sciences, Fuzhou 350003, China
  • Received:2020-05-06 Revised:2020-07-10 Online:2020-12-15 Published:2020-12-10

Abstract: White teas processed from fresh leaves of oolong tea cultivars can be always detected with flower flavor characteristics. In order to investigate the formation and changes of aroma components during the manufacture of such fragrant white tea, fresh leaves harvested from 10 oolong tea cultivars including Mingke1 were respectively processed into white teas under controlled indoor air conditions set at 18-22℃ and humidity of 45%-60%. Compared with traditional white teas produced from Fudingdahao-cha, Fuandabai-cha and Fuyun 6, the aroma components of white teas and the WIP (work in process) samples prepared according to the weight loss rate of fresh leaves from oolong tea cultivars were isolated by head space solids-phase micro-extraction (HS-SPME) and determined by gas chromatography-mass spectrometry (GC-MS) in combination with stoichiometric analysis. The results show that there were very different chemical patterns of aroma components between fragrant white teas and traditional white teas. The aroma patterns of white teas and in-process products obtained from oolong tea cultivars were of high similarity. With the increase of the weight loss rate of fresh leaves, the distribution of these tea samples in the two-dimensional score plot obtained from principal component analysis tended to disperse gradually, resulting in oriented migration as a group. It could be seen that the dynamic changes of aroma components during the processing of fragrant white tea were also closely related to the properties of the raw materials from each tea cultivars by cluster analysis. From 30% to 60% of the weight loss rate was the key development stage affecting the formation of aroma quality of fragrant white tea, especially for the weight loss rate≥45%. The 136 aroma components detected in tea samples from oolong tea cultivars were significantly enriched in three changing trend models, including linalool and its oxide, geraniol, geranial, methyl salicylate, β-ionone and dihydroactinidiolide and some other volatile components with pleasant flavor, which can be regarded as the most important chemical indicators for the coupling process to regulate aroma quality of fragrant white tea.

Key words: white tea, aroma component, withering, gas chromatography-mass spectrometry, pattern recognition

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