# Effect of Fermentation Humidity on Quality of Congou Black Tea
## 4 Conclusions  
It can be concluded that fermentation humidity mainly affects the appearance, aroma and taste quality of congou black tea (Figure 7). High humidity (85% or above) during fermentation is more conducive to the sensory qualities of congou black tea, with softer, moister fermented leaves, a tighter, drier appearance, a sweet and pure aroma and a stronger taste of sweetness and umami. This can be partly attributed to the oxidation of tea  
Figure 6: Correlation analysis of IC\({}_{50}\) values of DPPH, \(\alpha\)-amylase and \(\alpha\)-glucosidase with taste component contents, with red for positive correlation and blue for negative correlation; darker color and larger circle area indicate a larger correlation coefficient; \(\star\) indicates significant difference at \(p\) < 0.05.  
polyphenols, as well as the transformation of catechins, theaflavins, flavones and amino acids, plus the retention of soluble sugars. Additionally, it is also related to the increase of floral and fruity aroma substances, such as linalool, its oxides and nerol. Despite its stronger inhibitory effects on \(\alpha\)-amylase and \(\alpha\)-glucosidase activities and antioxidant activity against DPPH, the black tea fermented at low humidity (55-75%) showed poorer sensory quality. In summary, the biological activity of tea samples can be maintained by appropriately reducing the fermentation humidity without affecting the tea's sensory quality, so that drinking this kind of black tea can favor the recovery of the diabetic population. This study offered an effective theoretical foundation for processing high-quality congrou black tea under optimal fermentation humidity conditions.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/foods12081726/s1](https://www.mdpi.com/article/10.3390/foods12081726/s1)]([https://www.mdpi.com/article/10.3390/foods12081726/s1](https://www.mdpi.com/article/10.3390/foods12081726/s1)). Table S1: Effect of fermentation humidity on the chromatic aberration of congrou black tea's infusion; Table S2: Content of volatile compounds under different fermentation humidity conditions.  
**Author Contributions:** Conceptualization, S.Z. and D.N.; methodology, S.Z., X.J., Y.C. and Z.Y.; software, S.Z.; validation, C.L. and L.Q.; formal analysis, S.Z.; investigation, S.Z., C.L., L.Q. and X.J.; resources, D.N. and Z.Y.; data curation, S.Z. and X.J.; writing--original draft preparation, S.Z. and X.J.; writing--review & editing, S.Z., D.N. and Z.Y.; visualization S.Z. and X.J.; supervision, Y.C. and Z.Y.; project administration, D.N.; funding acquisition, D.N. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the National Key R&D Program of China (Project No. 2021 YFD1000401), National Natural Science Foundation of China (32272769), the Enshi State Technological Plan Project (D20210009), and the Key Projects of Science and Technology Cooperation in Jiangxi Province (20212 BDH80011).  
**Institutional Review Board Statement:** The study was carried out following the rules of the Declaration of Helsinki in accordance with Huazhong Agricultural University Human Ethics application ID Number: 202302200001.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data available in a publicly accessible repository. Data is contained within the article or supplementary material.  
Figure 7: Schematic diagram for the main effects of fermentation humidity on congrou black tea quality.  
**Acknowledgments:** We appreciate the National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops for the technical support and [PERSON] for his assistance and guidance in English editing.  
**Conflicts of Interest:** The authors declare no conflict of interest.