HS-SPME-GC-MS技术结合ROAV分析桐柏山野红茶的关键香气物质

Analysis of key aroma substances in Tongbai wild black tea using HS-SPME-GC-MS with ROAV

  • 摘要: 【目的】 揭示桐柏山野红茶与常规栽培红茶在相同加工工艺条件下挥发性成分的差异,并明确其特征香气物质,以期为桐柏地区野放茶树资源的高效开发利用及桐柏红茶香气品质的优化提供参考依据。【方法】 选取桐柏县2种野放茶树和4种常规栽培茶树的1芽2叶鲜叶为原料,按照相同工艺加工制作6个桐柏红茶样品,采用顶空固相微萃取—气相色谱—质谱联用(HS-SPME-GC-MS)技术对其挥发性成分组成进行解析,并鉴定其关键香气物质。【结果】 从6个桐柏红茶样品中共鉴定出115种挥发性成分,涵盖酯类(38种)、醇类(16种)、醛类(20种)、酮类(15种)、萜烯类(9种)、杂环类(7种)、酸类(6种)、苯酚类(3种)和其他类(1种)。对比发现,山野红茶(94种)的挥发性成分相较于常规栽培红茶(89种)更为丰富,但其相对含量低于常规栽培红茶。基于多元统计分析筛选鉴定出32种关键差异化合物变量投影重要性(VIP)>1、P<0.05,通过计算各化合物的相对气味活度值(ROAV)明确正己醛、(E)-3,7-二甲基-2,6-辛二烯醛、丙位壬内酯等16种气味活性化合物是造成山野红茶与常规栽培红茶香气品质差异的关键香气活性物质(ROAV>1)。其中,甲基庚烯酮(脂香、青香、柑橘气味,最高ROAV=103.13)和丙位壬内酯(椰子香,最高ROAV=562.80)是常规栽培红茶中贡献较大的气味活性物质;正己醛(果香、青香,最高ROAV=6785.00)、(E)-3,7-二甲基-2,6-辛二烯醛(柠檬香,最高ROAV=1175.43)和庚醛(果香、脂香,最高ROAV=232.53)是山野红茶中贡献较大的气味活性物质。【结论】 茶树受生长环境影响,桐柏山野红茶和常规栽培红茶挥发性成分及相对含量存在一定差异;山野红茶的重要香气贡献物质多于常规栽培红茶,贡献度更大,呈花香、甜香、果香等香型,香气质量更优,开发潜力大。

     

    Abstract: 【Objective】 This study aimed to investigate the differences in volatile components between Tongbai wild black tea and conventionally cultivated black tea under the same processing techniques, and to identify their characteristic aroma substances, so as to provide a scientific reference for developing and utilizing tea plant resources in the Tongbai region and optimizing aroma quality of Tongbai black tea.【Method】 Fresh samples of one bud and two leaves of two wild tea varieties and four conventionally cultivated Tongbai tea varieties as raw materials, and six Tongbai black tea samples were made using the same processing techniques. Headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS) was employed to analyze their volatile composition and identify key aroma substances.【Result】 A total of 115 volatile components were identified from the six Tongbai black tea samples, covering categories of esters (38), alcohols (16), aldehydes (20), ketones (15), terpenes (9), heterocyclics (7), acids (6), phenols (3), and others (1). Comparative analysis revealed a greater diversity of volatile components was found in the Tongbai wild black tea (94) than in conventionally cultivated tea (89), and the relative contents of volatile compounds in the Tongbai wild black tea were higher than those in cultivated tea. Multivariate statistical analysis identified 32 key differential compounds variable importance in projection (VIP)>1, P<0.05. By calculating the relative odor activity value (ROAV) of each compound, 16 aroma-active compounds (including hexanal, (E)-3,7- dimethyl-2,6-octadienal, and γ-nonanolactone) were determined as aroma-active substances (ROAV>1) leading to aroma quality differences between wild and cultivated Tongbai black tea. Methyl heptenone (fatty, green, citrus, with the max ROAV=103.13) and γ-nonanolactone (coconut-like, with a max ROAV=562.80) were major contributors in the conventionally cultivated tea; while hexanal (fruity, green, with the max ROAV=6785.00), (E)-3,7-dimethyl-2,6-octadienal (lemon, with the max ROAV=1175.43), and heptaldehyde (fruity, fatty, with the max ROAV=232.53) showed higher odor contributions in the wild tea.【Conclusion】 The growth environment significantly influences tea plants, leading to differences in volatile components and their relative contents between Tongbai wild black tea and the conventionally cultivated counterpart. Wild black tea contains more abundant aroma-contributing compounds with a greater contribution than conventionally cultivated tea. Its aroma profile, manifested as flowery, sweet, and fruity notes, is of higher quality, indicating potential for development.

     

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