# Characterization of the Key Aroma Compounds of Shandong Matcha Using HS-SPME-GC/MS and SAFE-GC/MS
## 3 Results
### Composition of Aromatic Substances in Shandong Matcha and Tencha  
In order to obtain more comprehensive volatile components to analyze and evaluate the aroma composition of matcha tea, headspace solid-phase microextraction (HS-SPME) and solvent-assisted flavor evaporation (SAFE) were both used to extract the volatile components of concentrated tea samples. A total of 705 volatile components were detected in this study, of which 199 volatile components were detected with the HS-SPME method, and 606 common components were detected using the SAFE method (Table S1). The volatile components detected with HS-SPME were mainly composed of 10 aromatics, 22 terpenoids, 45 hydrocarbons, 22 ketones, 28 heterocyclic compounds and 31 esters (Figure 2). The proportion of volatile components in different categories is listed in Table S1. In matcha, M-GS had the highest proportion of terpenoids, ketones, aldehydes and alcohols, while M-G1 and M-G2 had the highest proportion of aromatic hydrocarbons, acids and esters. In tencha, the proportion of alcohols, terpenoids, ketones and heterocyclic compounds in T-GS was the highest, while the proportions of aromatics, acids, hydrocarbons and esters in T-G1 and T-G2 were highest. On the whole, the proportion of esters, terpenoids, aldehydes and acids in Shandong matcha was lower than that in tencha, while the proportion of heterocyclic compounds was higher. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Tea Sample**} & \multicolumn{5}{c}{**Aroma Characteristics**} \\ \cline{2-7}  & **Fresh and Tender** & **Grassy and Harsh** & **Clean and Pure** & **Fatty and Dull** & **Roasted** & **High-Fired** \\ \hline M-GS & 4.86 \(\pm\) 0.38 \({}^{\ast}\) & 0.43 \(\pm\) 0.53 \({}^{\ast}\) & 4.86 \(\pm\) 0.38 \({}^{\ast}\) & 0.57 \(\pm\) 0.53 \({}^{\ast}\) & 4.57 \(\pm\) 0.53 \({}^{\ast}\) & 0.86 \(\pm\) 0.38 \({}^{\ast}\) \\ M-G1 & 4.57 \(\pm\) 0.53 \({}^{\ast}\) & 1.57 \(\pm\) 0.53 \({}^{\ast}\) & 4.43 \(\pm\) 0.53 \({}^{\ast}\) & 1.29 \(\pm\) 0.49 \({}^{\ast}\) & 3.14 \(\pm\) 0.38 \({}^{\ast}\) & 3.86 \(\pm\) 0.38 \({}^{\ast}\) \\ M-G2 & 2.57 \(\pm\) 0.53 \({}^{\ast}\) & 3.36 \(\pm\) 0.69 \({}^{\ast}\) & 2.86 \(\pm\) 0.69 \({}^{\ast}\) & 3.57 \(\pm\) 0.53 \({}^{\ast}\) & 2.14 \(\pm\) 0.69 \({}^{\ast}\) & 4.43 \(\pm\) 0.53 \({}^{\ast}\) \\ T-GS & 4.71 \(\pm\) 0.49 \({}^{\ast}\) & 1.29 \(\pm\) 0.49 \({}^{\ast}\) & 4.43 \(\pm\) 0.53 \({}^{\ast}\) & 1.00 \(\pm\) 0.00 \({}^{\ast}\) & 4.14 \(\pm\) 0.69 \({}^{\ast}\) & 1.57 \(\pm\) 0.53 \({}^{\ast}\) \\ T-G1 & 4.14 \(\pm\) 0.69 \({}^{\ast}\) & 1.43 \(\pm\) 0.53 \({}^{\ast}\) & 3.86 \(\pm\) 0.38 \({}^{\ast}\) & 1.57 \(\pm\) 0.53 \({}^{\ast}\) & 3.43 \(\pm\) 0.53 \({}^{\ast}\) & 2.71 \(\pm\) 0.49 \({}^{\ast}\) \\ T-G2 & 1.14 \(\pm\) 0.38 \({}^{\ast}\) & 4.41 \(\pm\) 0.69 \({}^{\ast}\) & 2.43 \(\pm\) 0.53 \({}^{\ast}\) & 3.86 \(\pm\) 0.38 \({}^{\ast}\) & 2.43 \(\pm\) 0.53 \({}^{\ast}\) & 4.43 \(\pm\) 0.53 \({}^{\ast}\) \\ \hline \hline \end{tabular}  
* Data are shown as the mean \(\pm\) standard deviation (\(n\) = 7). Different letters in each column represent significant difference (\(p\) < 0.05).  
\end{table} 
Table 1: Aroma characteristics and intensity description of Shandong matcha and tencha. The volatile components detected using SAFE were mainly composed of 41 alcohols, 42 aldehydes, 109 terpenoids, 46 ketones, 112 heterocyclic compounds and 92 esters and ethers were detected only using this method. In addition, 482 substances were unique to M-GS. In matcha, M-GS had the highest proportion of alcohols, aromatics, aldehydes, terpenoids and ketones, while M-G1 and M-G2 had the highest proportion of acids, hydrocarbons, heterocyclic compounds and esters. In tencha, the proportion of alcohols, aldehydes, terpenoids and ketones in T-GS was the highest, while the proportion of aromatics, acids and esters of T-G1 and T-G2 was higher than that of T-GS.