Drinking tea is beneficial to reduce the incidence of obesity. Unlike Fuzhuan brick tea (DT, a typical dark tea) widely reported to have good glycolipid-lowering activity (GLA), there is little information on GLA of Dancong summer tea (OT, a typical oolong tea). A comparative study on GLA and chemical compositions of OT and DT was systematically conducted. The results showed that OT had advantages in high content of polyphenols, leading to its better GLA including glycolipid digestion enzyme inhibitory activity and cholesterol micellar solubility inhibition activity than DT’s. A total of 21 compounds mainly including catechins, flavonoids, phenolic acids and phenylpropanoids were screened as the key differentially active micromolecules (KDAM) by UPLC-QTOF-MS/MS-based untargeted metabolomic analysis combined with multivariate analysis, which resulted in the difference of GLA between OT and DT. Moreover, the high affinity capacity and interaction mode between KDAM with α -glucosidase/ α -amylase/pancreatic lipase/cholesterol esterase were validated by molecular docking. Although the accumulation of polyphenols makes OT has a poor flavor as a beverage, our research demonstrated that OT with high content of polyphenols could be used in functional foods to facilitate the prevention of obesity.
One of the main factors constraining the growth of the tea business is the low use rate of summer tea. To enhance the utilization rate and improve the quality of summer tea, this study innovatively integrated shaking, freezing, and rolling into the traditional processing methods of white tea. Processing parameters were optimized through single-factor experiments combined with an L9(34) orthogonal experimental design. The quality of summer teas was systematically evaluated using sensory analysis, gas chromatography–mass spectrometry, and high-performance liquid chromatography. This study found that the optimal processing for summer tea was as follows: fresh leaves, room-temperature cold-air withering for 6.5 h, shaking at 10 rpm for 10 min, −20 °C freezing for 5 h, 25% strength rolling for 9 min, and drying at 75 °C for 2 h. The relative content of esterified catechins in summer tea produced by the optimal processing method was reduced by 14.62% compared with the control group. There were alterations in the content of amino acid components, with fresh and sweet amino acids increasing by 4.96% and 2.95%, respectively, and bitter amino acids reducing by 2.15%. Furthermore, γ-aminobutyric acid and L-theanine contents increased by 0.51% and 5.77%, respectively. Five characteristic volatile compounds were identified, namely, methyl salicylate, phenethyl formate, linalool, dimethyl sulfide, and isobutyraldehyde. The volatile profile was dominated by floral and fruity notes, except for dimethyl sulfide, which exhibited a distinct cooked corn-like aroma characteristic. This process was shown to improve the quality of summer tea. The results of this study provide a metabolite-level grounds for improving the quality of summer tea.
危险品化学品经营许可证（带存储）