基于溶剂辅助风味蒸发富集的茶香分析
Summary
这里介绍的是一种利用溶剂辅助风味蒸发和溶剂萃取，然后气相色谱-质谱法富集和分析茶提取物挥发性成分的方法，该方法可应用于所有类型的茶叶样品。
Abstract
茶香是影响茶叶品质的重要因素，但由于茶叶提取物挥发性成分的复杂性、低浓度、多样性和不稳定性，分析起来具有挑战性。本研究提出了一种利用溶剂辅助风味蒸发（SAFE）和溶剂萃取后气相色谱-质谱（GC-MS）来获取和分析茶叶提取物挥发性成分并保持气味的方法。SAFE是一种高真空蒸馏技术，可以从复杂的食品基质中分离挥发性化合物，而不会产生任何非挥发性干扰。本文介绍了茶叶香气分析的完整分步程序，包括茶叶输液制备、溶剂萃取、SAFE蒸馏、提取物浓缩和GC-MS分析。将该程序应用于两个茶样（绿茶和红茶），并获得茶样挥发性成分的定性和定量结果。该方法不仅可以用于各类茶样的香气分析，还可以用于茶样的分子感官研究。
Introduction
茶是全世界许多人的首选饮料1,2。茶的香气是茶叶的质量标准和价格决定因素3,4。因此，分析茶叶的香气组成和含量对茶叶的分子感官研究和质量控制具有重要意义。因此，香气成分分析已成为近年来茶叶研究中的一个重要课题5,6,7。
茶叶中香气成分的含量很低，一般只占茶叶干重的0.01%-0.05%8。此外，样品基质中的大量非挥发性组分会显著干扰气相色谱法9,10的分析。因此，样品制备程序对于分离茶中的挥发性化合物至关重要。分离和富集方法的关键考虑因素是最大限度地减少基质干扰，同时最大限度地保留样品的原始气味特征。
溶剂辅助风味蒸发（SAFE）最初由Engel，Bahr和Schieberle开发，是一种改进的高真空蒸馏技术，用于从复杂的食品基质中分离挥发性化合物11,12。连接到高真空泵的紧凑型玻璃组件（在 5 x 10−3 Pa 的典型工作压力下）可以有效地从溶剂提取物、油性食品和水性样品中收集挥发性化合物。
本文介绍了一种将SAFE技术与溶剂萃取相结合的方法，以从红茶输液中分离挥发性物质，然后使用GC-MS进行分析。
Protocol
1.内标的制备和茶叶浸泡液 储备溶液：将10.0mg对二甲苯-d10（见 材料表）溶解在10.0 mL无水乙醇中，制备内标的1,000 ppm储备溶液。 工作溶液：用纯水将1 mL储备溶液（步骤1.1）稀释至100 mL，制成10 ppm的内标工作溶液。注意：工作溶液必须在分析的同一天制备。 将3克茶叶（绿茶和红茶，见 材料表）放入锥形瓶中，并加入150毫升沸水。用?…
Representative Results
本节使用红茶和绿茶样品的香气分析示例来说明上述分析程序。 代表性的GC-MS色谱图如图3所示。图3A显示了一组正构烷烃，图3B显示了内标的概况。绿茶和红茶样品提取物的评估结果分别显示在图3C和图3D中。通过分析内标，可以检测到一个具有稳定基线的确定峰（…
Discussion
本文介绍了一种使用SAFE和GC-MS分析分析茶叶输液中挥发性化合物的有效方法。
茶叶输液具有复杂的基质，具有高含量的非挥发性成分。文献中已经描述了几种从茶叶输液中分离挥发性成分的方法。一种常用的方法是同时蒸馏萃取（SDE）15,16。然而，它不适合分析茶香气，因为在整个蒸馏/提取过程中必须用水煮茶叶，这会导致茶叶成…
Disclosures
The authors have nothing to disclose.
Acknowledgements
这项研究得到了中国国家自然科学基金（32002094,32102444），财政部和MARA的中国农业研究系统（CARS-19）以及中国农业科学院创新项目（CAAS-ASTIP-TRI）的支持。
Materials
| Alkane mix (C10-C25) | ANPEL | CDAA-M-690035 | |
| Alkane mix (C5-C10) | ANPEL | CDAA-M-690037 | |
| AMDIS | National Institute of Standards and Technology | version 2.72 | Gaithersburg, MD |
| Analytical balance | OHAUS | EX125DH | |
| Anhydrous ethanol | Sinopharm | ||
| Anhydrous sodium sulfate | aladdin | ||
| Black tea | Qianhe Tea | Huangshan, Anhui province, China | |
| Concentrator | Biotage | TurboVap | |
| Data processor | Agilent | MassHunter | |
| Dichloromethane | TEDIA | ||
| GC | Agilent | 7890B | |
| GC column | Agilent | DB-5MS | |
| Green tea | Qianhe Tea | Huangshan, Anhui province, China | |
| MS | Agilent | 5977B | |
| p-Xylene-d10 | Sigma-Aldrich | ||
| SAFE | Glasbläserei Bahr | ||
| Ultra-pure deionized water | Milipore | Milli-Q | |
| Vacuum pump | Edwards | T-Station 85H |
References
- Liang, S., et al. Processing technologies for manufacturing tea beverages: From traditional to advanced hybrid processes. Trends in Food Science & Technology. 118, 431-446 (2021).
- Guo, X. Y., Ho, C. T., Schwab, W., Wan, X. C. Aroma profiles of green tea made with fresh tea leaves plucked in summer). Food Chemistry. 363, 130328 (2021).
- Feng, Z. H., Li, M., Li, Y. F., Wan, X. C., Yang, X. G. Characterization of the orchid-like aroma contributors in selected premium tea leaves. Food Research International. 129, 108841 (2020).
- Hong, X., et al. Characterization of the key aroma compounds in different aroma types of Chinese yellow tea. Foods. 12 (1), 27 (2023).
- Flaig, M., Qi, S. C., Wei, G., Yang, X., Schieberle, P. Characterisation of the key aroma compounds in aLongjinggreen tea infusion (Camellia sinensis) by the sensomics approach and their quantitative changes during processing of the tea leaves. European Food Research and Technology. 246 (12), 2411-2425 (2020).
- Feng, Z., et al. Tea aroma formation from six model manufacturing processes. Food Chemistry. 285, 347-354 (2019).
- Wang, J. -. Q., et al. Effects of baking treatment on the sensory quality and physicochemical properties of green tea with different processing methods. Food Chemistry. 380, 132217 (2022).
- Zhai, X., Zhang, L., Granvogl, M., Ho, C. -. T., Wan, X. Flavor of tea (Camellia sinensis): A review on odorants and analytical techniques. Comprehensive Reviews in Food Science and Food Safety. 21 (5), 3867-3909 (2022).
- Chaturvedula, V. S. P., Prakash, I. The aroma, taste, color and bioactive constituents of tea. Journal of Medicinal Plants Research. 5 (11), 2110-2124 (2011).
- Ridgway, K., Lalljie, S. P. D., Smith, R. M. Sample preparation techniques for the determination of trace residues and contaminants in foods. Journal of Chromatography A. 1153 (1-2), 36-53 (2007).
- Engel, W., Bahr, W., Schieberle, P. Solvent assisted flavour evaporation – A new and versatile technique for the careful and direct isolation of aroma compounds from complex food matrices. European Food Research and Technology. 209 (3-4), 237-241 (1999).
- Wang, B., et al. Characterization of aroma compounds of Pu-erh ripen tea using solvent assisted flavor evaporation coupled with gas chromatography-mass spectrometry and gas chromatography-olfactometry. Food Science and Human Wellness. 11 (3), 618-626 (2022).
- Zou, C., et al. Zijuan tea- based kombucha: Physicochemical, sensorial, and antioxidant profile. Food Chemistry. 363, 130322 (2021).
- Vandendool, H., Kratz, P. D. A generalization of the retention index system including linear temperature programmed gas-liquid partition chromatography. Journal of Chromatography. 11, 463-471 (1963).
- Khvalbota, L., Virba, M., Furdikova, K., Spanik, I. Simultaneous distillation-solvent extraction gas chromatography-mass spectrometry analysis of Tokaj Muscat Yellow wines. Separation Science Plus. 5 (8), 393-406 (2022).
- Ayalew, Y., et al. Volatile organic compounds of anchote tuber and leaf extracted using simultaneous steam distillation and solvent extraction. International Journal of Food Science. 2022, 3265488 (2022).
- Zhu, M., Li, E., He, H. Determination of volatile chemical constitutes in tea by simultaneous distillation extraction, vacuum hydrodistillation and thermal desorption. Chromatographia. 68 (7-8), 603-610 (2008).
- Lau, H., et al. Characterising volatiles in tea (Camellia sinensis). Part I: Comparison of headspace-solid phase microextraction and solvent assisted flavour evaporation. Lwt-Food Science and Technology. 94, 178-189 (2018).
- Li, Z. W., Wang, J. H. Analysis of volatile aroma compounds from five types of Fenghuang Dancong tea using headspace-solid phase microextraction combined with GC-MS and GC-olfactometry. International Food Research Journal. 28 (3), 612-626 (2021).
- Dong, F., et al. Herbivore-induced volatiles from tea (Camellia sinensis) plants and their involvement in intraplant communication and changes in endogenous nonvolatile metabolites. Journal of Agricultural and Food Chemistry. 59 (24), 13131-13135 (2011).
- Acena, L., Vera, L., Guasch, J., Busto, O., Mestres, M. Comparative study of two extraction techniques to obtain representative aroma extracts for being analysed by gas chromatography-olfactometry: Application to roasted pistachio aroma. Journal of Chromatography A. 1217 (49), 7781-7787 (2010).
- Kumazawa, K., Wada, Y., Masuda, H. Characterization of epoxydecenal isomers as potent odorants in black tea (Dimbula) infusion. Journal of Agricultural and Food Chemistry. 54 (13), 4795-4801 (2006).
- Wu, H. T., et al. Effects of three different withering treatments on the aroma of white tea. Foods. 11 (16), 2502 (2022).
- Wang, J., et al. Decoding the specific roasty aroma Wuyi rock tea (Camellia sinensis: Dahongpao) by the sensomics approach. Journal of Agricultural and Food Chemistry. 70 (34), 10571-10583 (2022).
Cite This Article
Feng, Z., Yang, X., Zou, C., Yin, J. Tea Aroma Analysis Based on Solvent-Assisted Flavor Evaporation Enrichment. J. Vis. Exp. (195), e65522, doi:10.3791/65522 (2023).