Yellow tea is one of the six major tea categories in China. The floral fragrance type, high-fired fragrance type, fresh fragrance type, and corn-like fragrance type were the main aroma types of yellow tea screened by QDA. A total of 103 volatiles were identified in yellow teas by HS-SPME/GC-MS analysis. Using multivariate analysis and OAVs, forty-seven aroma compounds were identified as key aroma compounds for the formation of different aroma types of yellow teas. Among them, 8, 14, 7, and 18 key aroma compounds played an important role in the formation of aroma characteristics of floral fragrance, high-fired fragrance, fresh fragrance, and corn-like fragrance types of yellow teas, respectively. Furthermore, PLS analysis revealed that 12 aroma compounds were the key contributors to the ‘floral and fruity’ and ‘sweet’ attributes, five aroma compounds contributed to the ‘roasted’ attribute, and four aroma compounds related to the ‘fresh’ and ‘grassy’ attributes. This study provides new insights into the aroma characteristics formation of different aroma types of yellow teas and will provide a valuable theoretical basis for improving the flavor quality of yellow tea during the manufacturing process.

The aroma profile of sun-dried black tea (SBT) was identified by headspace solid–phase microextraction (HS–SPME) coupled with gas chromatography–mass spectrometry (GC–MS) and gas chromatography–olfactometry (GC–O). A total of 37 scents were captured by using the GC–O technique, and 35 scents with odor intensities ranging from 1.09 ± 1.93 to 9.91 ± 0.29 were identified. Twenty-one compounds were further identified as key odor-active compounds with odor activity values (OAVs) greater than or equal to one. These key odor-active compounds were restructured with their detected concentrations, and the aroma profile of the selected SBT sample was successfully imitated to a certain extent. An omission test was performed by designing 25 models and confirmed that (E)-β-damascenone, β-ionone, dihydro-β-ionone, linalool, and geraniol were the key odor-active compounds for the aroma profile of SBT. Meanwhile, phenylethyl alcohol, (E)-2-decenal, hexanal, and methyl salicylate were also important to the aroma profile of SBT. This study can provide theoretical support for the improvement of the aroma quality of sun-dried black tea.

A new method based on solid-phase extraction (SPE) combined with headspace solid-phase microextraction (HS-SPME) was established for the determination of terpenes in Baijiu. Terpenes were concentrated on the C18 solid-phase extraction column, and an additional enrichment of the terpenes was performed using HS-SPME for fillers of the C18 solid-phase extraction column. The conditions of the SPE and SPME were optimized, and the optimal conditions were using the Thermo C18 extraction column, elution water of 1 mL, an extraction temperature of 70°C, and an extraction time of 50 min. Under these optimal conditions, four terpenes were randomly selected to verify the analytical method in terms of linearity, the limit of detection, the limit of quantification, precision, and accuracy. The results showed that the SPE-HS-SPME method has high sensitivity and a high recovery rate, which was also accurate and reliable in the quantitative analysis. It is a feasible new method for the detection of terpene substances in Baijiu. Graphical Abstract