## 2 Results and Discussion
### Volatile Components in HAB
#### 2.3.3 Sulfides  
Volatile sulfides play a remarkable role in the aroma of food and beverages, even when present at low concentrations [39; 40]. Recently, [PERSON] et al. found that the imbalance of sulfides will lead to the off-odor in soy sauce aroma-type Baijiu; however, these compounds might contribute to the overall aroma of Baijiu at relatively low concentrations [41]. In this study, a total of 37 sulfides (Table 3) were identified, of which 28 compounds have not been reported before in Baijiu. Sulfides usually have a relatively low odor threshold and contribute to the onion, cabbage, and sulfur aroma. Dimethyl trisulfide is an important sulfide in Baijiu, and it is well known for the onion and cabbage aroma with an odor threshold of 0.36 ug/L [42]. Methoinal is characterized by cooked potatoes and has a perception  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline
**NO.** & **Compounds** & **RT1 a** & **RT2 b** & **Similarity** & **LRIcal c** & **LRIlit d** & **Identification e** \\ \hline
54 & Nerol & 2072 & 1.7 & 845 & 1811 & 1821 & RI, MS, Tent \\
55 & Isogeraniol & 2096 & 1.69 & 832 & 1827 & 1818 & RI, MS, Tent \\
56 & \(\beta\)-Damascenone & 2104 & 2.26 & 910 & 1832 & 1827 & RI, MS, STD \\
57 & Dihydro-\(\beta\)-ionone & 2124 & 2.36 & 835 & 1845 & 1854 & RI, MS, Tent \\
58 & \(\updownarrow\)-calamenene & 2124 & 2.81 & 946 & 1846 & 1838 & RI, MS, STD \\
59 & Geraniol & 2132 & 1.7 & 872 & 1850 & 1851 & RI, MS, STD \\
60 & _trans_-Geranylacetone & 2148 & 2.19 & 877 & 1861 & 1862 & RI, MS, STD \\
61 & Geosmin & 2148 & 2.32 & 902 & 1861 & 1858 & RI, MS, STD \\
62 & \(\alpha\)-Ionone & 2156 & 2.2 & 846 & 1866 & 1866 & RI, MS, STD \\
63 & \(\alpha\)-Dehydro-himachalene & 2184 & 2.61 & 836 & 1885 & 1882 & RI, MS, Tent \\
64 & \(\alpha\)-Calacorene & 2248 & 2.53 & 898 & 1930 & 1904 & RI, MS, Tent \\
65 & Palustrol & 2264 & 2.46 & 899 & 1941 & 1938 & RI, MS, Tent \\
66 & _trans_-\(\beta\)-Ionone & 2280 & 2.15 & 854 & 1952 & 1953 & RI, MS, STD \\
67 & _cis_-Jasmone & 2292 & 1.99 & 859 & 1961 & 1955 & RI, MS, STD \\
68 & \(\beta\)-Caryophyllene oxide & 2296 & 2.17 & 792 & 1964 & 1990 & RI, MS, Tent \\
69 & p-Nerolidol & 2388 & 1.84 & 921 & 2036 & 2010 & RI, MS, Tent \\
70 & E-Nerolidol & 2392 & 1.82 & 926 & 2040 & 2054 & RI, MS, Tent \\
71 & Epicubenol & 2436 & 2.07 & 765 & 2077 & 2078 & RI, MS, Tent \\
72 & \(\alpha\)-Corocalene & 2436 & 2.15 & 863 & 2077 & 2083 & RI, MS, Tent \\
73 & Cubenol & 2436 & 2.07 & 787 & 2077 & 2071 & RI, MS, Tent \\
74 & 6-Isocedrol & 2496 & 1.95 & 894 & 2135 & 2162 & RI, MS, Tent \\
75 & \(\alpha\)-Cedrol & 2496 & 1.95 & 877 & 2135 & 2127 & RI, MS, Tent \\
76 & \(\beta\)-Bisabolol & 2520 & 1.82 & 728 & 2160 & 2151 & RI, MS, Tent \\
77 & Torreyl & 2556 & 1.92 & 815 & 2197 & 2197 & RI, MS, Tent \\
78 & \(\alpha\)-Cadinol & 2556 & 1.92 & 810 & 2197 & 2217 & RI, MS, STD \\
79 & \(\alpha\)-Eudesmol & 2592 & 1.98 & 719 & 2237 & 2223 & RI, MS, Tent \\
80 & \(\beta\)-Eudesmol & 2600 & 2 & 821 & 2246 & 2246 & RI, MS, Tent \\
81 & Farnesol & 2700 & 1.95 & 846 & 2353 & 2351 & RI, MS, Tent \\
82 & 9H-Fluorene & 2732 & 2.16 & 907 & 2386 & 2374 & RI, MS, Tent \\ \hline \end{tabular}  
* RT1: retention time on the primary column. b RT2: retention time on the secondary column. c IRIcal: calculated linear retention indices. d LRIlit: literature linear retention indices obtained from the NIST library ([[https://webbook.nist.gov/chemistry](https://webbook.nist.gov/chemistry)]([https://webbook.nist.gov/chemistry](https://webbook.nist.gov/chemistry))). e Identification: tentative identification (Tent.) based on retention indices (RI) and mass spectra (MS), positive identification based on retention times of authentic standards (STD).  
\end{table}
Table 2: Cont.  
threshold of 7.1 ug/L [42]. Several sulfides were first reported in HAB, and s-methyl ester butanethoic acid shows a sulfarous and cheesy aroma [43], 5-Methyl-2-formylthiophene is described as moldy odor, and 1,2,4-trithiolane contributes the roasted beef and sulfarous aroma.