Aromatic Quality and Suitability of Three Tea Varieties for Making Black Tea

Objective Potential of three tea varieties for making black tea was evaluated based on the suitability for processing of the leaves and aromatic quality of the tea made.

Method Sensory evaluation was conducted on the black teas made with the leaves plucked from tea bushes of the red-purple bud Jinmingzao and Fengyang-ziya, the green bud Changle-daye, as well as the control varieties Huangdan and Fuding-dabaicha. Aromatics in the teas were analyzed using automatic thermal desorption-gas chromatography-mass spectrometry (ATD-GC-MS) to compare and evaluate the application potential with the methods of odor activity value (OAV), heat maps, and multivariate statistics.

Result Fifty volatiles of floral and fruity notes including linalool, benzyl alcohol, decanal, geraniol, nonanal, and 2-methylbutanal were detected in the Jinmingzao black tea; 42 aromatics of similar characteristics that dominated by linalool, benzyl alcohol, 2-methylbutanal, geraniol, decanal, 1-hexanol, 1-octanol, isovaleraldehyde, and phenylethanal identified in the Fengyang-ziya black tea; and 39 fresh floral fragrance compounds, such as linalool, decanal, nonanal, geraniol, benzyl alcohol, and 2-methylbutanal, found in the Changle-daye black tea. The sensory evaluation panel characterized the Jinmingzao black tea to be strongly fragrant, the Fengyang-ziya floral, and the Changle-daye woody and fresh. In comparison, the heatmap analysis also showed significant differences in aromatics among the black teas, and the OPLS-DA model clearly differentiated those made from the red-purple bud varietIies (Jinmingzao and Fengyang-ziya) and the green bud counterparts (Changle-daye, Huangdan and Fuding-dabaicha). The OAVs of the black teas indicated that Jinmingzao not only had the widest variety of floral and fruity-scented alcohols but included exclusively the sweet floral trans-nerolidol, while Changle-daye had the compounds with distinctive woody and fresh notes like isophorone, α-ionone, and α-pinene as well as a high content of freshly floral scent of linalool.

Conclusion The three tea varieties tested as new raw material for making black tea significantly differed in the type and content of aromatics. The black teas of red-purple bud Jinmingzao and Fengyang-ziya were rich in substances like esters of floral and fruity notes and strongly fragrant. Whereas the black tea made from the green bud Changle-daye was light and delicately floral.