# Analysis of the Changes in Volatile Components During the Processing of Enshi Yulu Tea
## 4 Conclusions  
We used HS-SPME-GC/MS to analyze the aroma components of Enshi Yulu tea during processing. The 242 identified volatile compounds included 45 esters, 43 alcohols, 41 ketones, 32 alkenes, 20 aldehydes, 18 alkanes, 15 aromatic hydrocarbons, 10 oxygen heterocycles, 7 lactones, 6 nitrogen heterocycles, and 5 acids. From fresh leaves to the shaping stage, there were significant decreases in the contents of overall aroma substances, although these increased after drying. Linalool had the highest relative content (12.35%), followed by compounds such as geraniol (7.41%), 2,6-dimethylhept-5-enal (6.93%), phenylmethanol (5.98%), isobutyl acetate (4.16%), hexan-1-ol (3.95%), 2-phenylacetaldehyde (3.80%), and oct-1-en-3-ol (3.33%). During the steaming process, there were 159 differential volatile components, of which 20 were up-regulated, and 139 were down-regulated. During the rolling process, all 24 differential volatile components were down-regulated; of 116 differential volatile components during the shaping process, 60 were up-regulated, and 51 were down-regulated; during the drying process, 68 of the 81 differential volatile components were up-regulated, and 13 were down-regulated. Most variation occurred after steaming, and the least variation occurred after rolling.  
PLS-DA analysis revealed significant variation in aroma components during the processing stages of Enshi Yulu tea and identified 100 compounds with higher relative contents. These compounds followed five distinct patterns of change, with phenylmethanol, 2-phenylacetaldehyde, (_2E_)-non-2-enal, oct-1-en-3-ol, and _cis_-3-hexenyl hexanoate exerting a profound impact on the overall aroma quality. These findings improve our knowledge of chemical theories related to tea aroma quality and deepen our understanding of mechanisms responsible for aroma formation in steamed green teas  
**Supplementary Materials:** The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/foods13233968/s1](https://www.mdpi.com/article/10.3390/foods13233968/s1)]([https://www.mdpi.com/article/10.3390/foods13233968/s1](https://www.mdpi.com/article/10.3390/foods13233968/s1)). Table S1: List of 242 identified volatile compounds and their contents during the processing of Enshi Yulu tea; Table S2: The differential volatile compound in the processing stages of Enshi Yulu tea; Figure S1. CV distribution of each group; Figure S2. The essential spectrum detection of TIC overlap in the QC sample.  
**Author Contributions:** Conceptualization, A.G. and F.Y.; methodology, A.G. and F.Y.; software, A.G. and P.L.; validation, J.X. ([PERSON]), J.T., L.F. and X.W.; formal analysis, A.G.; investigation, S.W. and J.X. ([PERSON]); resources, S.G. and P.Z.; data curation, A.G.; writing--original draft preparation, A.G. and F.Y.; writing--review and editing, S.G. and F.Y.; visualization, A.G.; supervision, F.Y.; project administration, S.G. and P.Z.; funding acquisition, S.G. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported by National Key Research and Development Program of China (2022 YED1600804), China Agriculture Research System of MOF and MARA(CARS-19), Technology innovation plan project of Hubei Province (2024 BBB081), Hubei Rural Revitalization Strategy and Technology Support Project (2022 BBA113), Wuhan Key Research and Development Plan Project (Pair Assistance) (2022023102015164).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.  
**Acknowledgments:** The authors appreciate MetWare corporation (Wuhan, China) for providing the volatile component analysis.  
**Conflicts of Interest:** The authors declare no conflicts of interest.