Characterization of different grades of Jiuqu hongmei tea based on flavor profiles using HS-SPME-GC-MS combined with E-nose and E-tongue

In order to distinguish different grades of Jiuqu hongmei tea (black tea), four different grades of Jiuqu hongmei tea were used as materials in this study: Super Grade (SuG), First Grade (FG), Second Grade (SG), and Grade (TG). HS-SPME-GC-MS combined with electronic nose (E-nose) and electronic tongue (E-tongue) nology was used to detect and analyze tea samples. The results showed that 162 volatile substances identified, mainly alcohols, followed by hydrocarbons, aldehydes, ketones and esters. Twenty-nine volatile compounds were found in all grades of tea samples. The results of heat map analysis showed that the contents of five volatile compounds in different grades of Jiuqu hongmei tea were positively correlated with grades of Jiuqu hongmei tea. By orthogonal partial least squares discriminant analysis (OPLS-DA), 35 different compounds of SuG and FG, 30 different compounds of SG and TG, 34 different compounds of FG and SG found. Overall, the results indicated that there were significant differences in volatile compounds different grades of Jiuqu hongmei tea, and the use of HS-SPME-GC-MS combined with E-nose and E-tongue provide a scientific reference method as an effective tool for detecting flavor characteristics of other types black tea grades.

Automated summary

In this study, four different grades of Jiuqu hongmei tea were analyzed using HS-SPME-GC-MS, electronic nose, and electronic tongue. A total of 162 volatile substances were identified, with alcohols being the most abundant. Heat map analysis showed a positive correlation between the contents of five volatile compounds and the grades of Jiuqu hongmei tea. Orthogonal partial least squares discriminant analysis revealed different compounds between different grades of tea. Overall, this study demonstrated significant differences in volatile compounds among different grades of Jiuqu hongmei tea and provided a scientific method for detecting flavor characteristics in other black tea grades using HS-SPME-GC-MS, electronic nose, and electronic tongue.