从香气和对输液颜色的影响方面,将茶毛状体作为反映茶风味品质的重要评价指标。这项研究揭示了金色氧化毛状体对颜色的影响,通过比较代谢组学结合对红比洛(缺乏毛状体的黑茶)的定量分析,获得了红茶的挥发性和非挥发性代谢产物,红金洛(富含毛状体的红茶),和毛状体(来自红金洛)。采用顶空固相微萃取气相色谱-质谱联用技术检测了46种挥发性成分,而结果表明毛状体对红茶的贡献有限。共鉴定出60种标记性非挥发性化合物,包括儿茶素,儿茶素氧化产物,类黄酮苷,有机酸,可水解单宁和氨基酸。值得注意的是,对香豆酰基山奈酚葡糖苷,和儿茶素二聚体在独立的毛状体中表现出高水平,并与红茶浸液的亮度和黄色色调呈正相关,特别是山奈酚3-O-二-(对香豆酰基)-己糖苷。此外,分离毛状体的分级提取分析结果提供了N-乙基-2-吡咯烷酮取代的表儿茶素没食子酸酯,酰化山奈酚苷,和显色儿茶素二聚体,比如茶黄素,是氧化毛状体的主要颜色贡献者。尤其是,我们发现表儿茶素没食子酸酯(ECG)及其衍生物,3'-O-甲基-ECG和N-乙基-2-吡咯烷酮取代的ECG,高度积累在毛状体,这可能与红碧罗和红金落红茶的品种有关。最终,添加试验用于验证毛状体混合物的颜色贡献。我们的发现采用了全面的信息,揭示了金色氧化毛状体对红茶浸液的亮度和黄色色调做出了显着贡献。但是它们对香气和代谢特征的贡献是有限的。这些发现可能有助于通过调节茶毛状体的比例或筛选富含毛状体或缺乏毛状体的品种来有效调节红茶生产过程中的输液颜色。
Tea trichomes were regarded as an essential evaluation index for reflecting tea flavor quality in terms of aroma and influence on infusion color. This study reveals the impact of golden oxidized trichomes on the color, volatile and non-volatile metabolites of black teas through comparative metabolomics combined quantitative analysis on hongbiluo (trichomes-deficiency black teas), hongjinluo (trichomes-rich black teas), and trichomes (from hongjinluo). Forty-six volatile components were detected using headspace solid-phase microextraction gas chromatography-mass spectrometry, while the results suggested that the contribution of trichomes to black teas is limited. A total of 60 marker non-volatile compounds were identified, including catechins,
catechin oxidation products, flavonoid glycosides, organic acids, hydrolysable tannins and amino acids. Notably, p-coumaroyl-kaempferol glucosides, and
catechin dimers demonstrated high levels in independent trichomes and showed a positive correlation with the brightness and yellow hue of black tea infusions, specifically kaempferol 3-O-di-(p-coumaroyl)-hexoside. Furthermore, results from fractional extraction analysis of separated trichomes provided that N-ethyl-2-pyrrolidinone-substituted epicatechin gallates, acylated kaempferol glycosides, and chromogenic catechins dimers, such as theaflavins, were primary color contributors in oxidized trichomes. Especially, we found that epicatechin gallate (ECG) and its derivates, 3\'-O-methyl-ECG and N-ethyl-2-pyrrolidinone-substituted ECG, highly accumulated in trichomes, which may be associated with the varieties of hongbiluo and hongjinluo black teas. Eventually, addition tests were applied to verify the color contribution of trichome mixtures. Our findings employed comprehensive information revealing that golden oxidized trichomes contributed significantly to the brightness and yellow hue of black tea infusion, but their contribution to the aroma and metabolic profile is limited. These findings may contribute to the effective modulation of the infusion color during black tea production by regulating the proportion of tea trichomes or screening trichomes-rich or deficiency varieties.