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茶树新品系金茗早、凤阳紫芽、长乐大叶红茶香气成分比较及适制性分析

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

  • 摘要:
    目的 对金茗早、凤阳紫芽、长乐大叶新品系红茶的香气成分进行鉴定分析,为茶树新品种选育与示范推广提供科学依据。
    方法 以‘黄棪’‘福鼎大白茶’为对照种,对‘金茗早’‘凤阳紫芽’‘长乐大叶’等3个品系鲜叶制作的红茶进行感官审评,并采用自动热脱附-气相色谱-质谱联用(Automatic thermal desorption-gas chromatography-mass spectrometry, ATD-GC-MS)方法进行香气成分测定,结合香气活性值(Odor activity value, OAV)、热图、多元统计等分析方法对不同品种(系)红茶香气成分及其差异进行分析。
    结果 金茗早红茶共检测出50种香气成分,其主要香气成分是以花香、果香为主的芳樟醇、苯甲醇、癸醛、香叶醇、壬醛、2-甲基丁醛;凤阳紫芽红茶共检测出42种香气成分,其主要香气成分是以花香、果香为主的芳樟醇、苯甲醇、2-甲基丁醛、香叶醇、癸醛、正己醇、辛醇、异戊醛、苯乙醛;长乐大叶红茶共检测出39种香气成分,其主要香气成分是以清花香为主的芳樟醇、癸醛、壬醛、香叶醇、苯甲醇、2-甲基丁醛。感官审评结果显示,金茗早红茶花香馥郁,凤阳紫芽红茶有花香,长乐大叶红茶具有特殊的木香、清香。热图分析结果表明,不同品种(系)红茶的香气成分存在显著差异。OPLS-DA模型可有效区分出紫芽种(金茗早、凤阳紫芽)和绿色芽叶种(长乐大叶、黄棪、福鼎大白茶)红茶,且判别效果好。OAV分析结果表明,呈花香、果香的醇类物质在金茗早红茶中种类最多,且呈甜花香的反式-橙花叔醇仅在金茗早红茶中检测出,形成了金茗早红茶花香馥郁的特征;呈现特殊木质香、清香的异佛尔酮、α-紫罗酮、α-蒎烯等香气物质对长乐大叶红茶的贡献度较大,且带有清花香的芳樟醇OAV值较高,形成了长乐大叶红茶特殊的木香、清香,可见茶叶感官审评结果与香气物质分析结果相一致。
    结论 3个茶树新品系红茶香气物质,在种类及含量上存在显著差异,红紫色芽叶品种红茶的香气成分更丰富,尤其在具有怡人花果香的酯类物质上,其含量和种类均显著优于绿色芽叶品系红茶。紫色芽叶品系金茗早、凤阳紫芽更适制高香型红茶,绿色芽叶品系长乐大叶则适制清香型红茶。

     

    Abstract:
    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.

     

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