## 2 Results and Discussion
### Volatile Components in HAB
#### 2.3.4 Cyclic Components
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No** & **Compounds** & **RT1 1a** & **RT2 b** & **Similarity** & **LRIcal c** & **LRIIit d** & **Identification e** \\ \hline
1 & Methanethiol & 292 & 1.34 & 985 & 669 & 643 & RI, MS, STD \\
2 & Dimethyl sulfide & 316 & 1.43 & 895 & 750 & 774 & RI, MS, STD \\
3 & Methyl thiolacetate & 628 & 1.69 & 814 & 1054 & 1052 & RI, MS, Tent \\
4 & Dimethyl disulfide & 668 & 1.81 & 960 & 1077 & 1078 & RI, MS, STD \\
5 & 5-Methyl propenothioate & 752 & 1.95 & 749 & 1122 & 1131 & RI, MS, STD \\
6 & Methyl ethyl disulfide & 804 & 2.05 & 736 & 1149 & 1141 & RI, MS, Tent \\
7 & \(S\)-Methyl ester butanethioic acid & 908 & 2.13 & 835 & 1201 & 1198 & RI, MS, STD \\
8 & Thiazole & 1032 & 1.59 & 907 & 1261 & 1259 & RI, MS, STD \\
9 & Dimethyl trisulphide & 1312 & 2.16 & 966 & 1399 & 1400 & RI, MS, STD \\
10 & 5-Methyl hexanethiolate & 1340 & 2.37 & 895 & 1414 & 1412 & RI, MS, Tent \\
11 & Methyl pentyl disulfide & 1400 & 2.48 & 764 & 1445 & 1445 & RI, MS, Tent \\
12 & 4,5-Dimethyl-2-isopropyl-thiazol & 1424 & 2.47 & 747 & 1457 & 1436 & RI, MS, Tent \\
13 & Ethyl 2-(methylthio)acetate & 1428 & 1.88 & 902 & 1459 & 1484 & RI, MS, STD \\
14 & Methional & 1448 & 1.72 & 826 & 1470 & 1480 & RI, MS, STD \\
15 & 2-Pentyl-thiophene & 1448 & 2.51 & 893 & 1470 & 1452 & RI, MS, Tent \\
16 & Furfuryl methyl sulfide & 1504 & 1.87 & 913 & 1499 & 1492 & RI, MS, Tent \\
17 & 4,5-Dimethyl-2-isobutythiiazole & 1568 & 2.57 & 709 & 1534 & 1514 & RI, MS, Tent \\
18 & 2-(Methylthio)ethanol & 1576 & 1.5 & 725 & 1538 & 1520 & RI, MS, Tent \\
19 & Methyl proply trisulfide & 1588 & 2.47 & 752 & 1545 & 1529 & RI, MS, Tent \\
20 & Ethyl 3-(methylthio)propionate & 1644 & 2 & 961 & 1575 & 1580 & RI, MS, STD \\
21 & 2,5-Dimethyl-1,3,4-trithiolane & 1724 & 2.32 & 865 & 1619 & 1618 & RI, MS, Tent \\
22 & 3-(Methylthio)propyl acetate & 1760 & 1.99 & 752 & 1639 & 1627 & RI, MS, Tent \\
23 & 2,4,5-Tithiahexane & 1828 & 2.26 & 895 & 1676 & 1662 & RI, MS, Tent \\
24 & Methyl benzyl sulfide & 1836 & 2.36 & 932 & 1680 & 1665 & RI, MS, STD \\
25 & 3-Thiopheneexboxyldehyde & 1868 & 1.77 & 711 & 1697 & 1687 & RI, MS, Tent \\
26 & 2-Thiopheneexboxyldehyde & 1896 & 1.73 & 920 & 1713 & 1722 & RI, MS, STD \\
27 & Methionol & 1916 & 1.56 & 914 & 1724 & 1721 & RI, MS, STD \\
28 & 5-Methyl-2-formylthiophene & 1932 & 1.9 & 814 & 1733 & 1759 & RI, MS, Tent \\
29 & Dimethyl tetrasulphide & 1988 & 2.32 & 727 & 1763 & 1750 & RI, MS, Tent \\
30 & 1,2,4-Tithiolane & 2004 & 2 & 866 & 1772 & 1760 & RI, MS, Tent \\
31 & 3-Acetylthiophene & 2044 & 1.75 & 752 & 1794 & 1772 & RI, MS, Tent \\
32 & 2-Acetylthiophene & 2044 & 1.74 & 717 & 1794 & 1785 & RI, MS, STD \\
33 & Furfuryl methyl disulfide & 2088 & 1.94 & 846 & 1822 & 1813 & RI, MS, Tent \\
34 & 3-Methyl-2-thiophenexaldehyde & 2104 & 1.76 & 798 & 1832 & 1815 & RI, MS, Tent \\
35 & 1-(2-Thienyi) propanone & 2144 & 1.8 & 714 & 1858 & 1840 & RI, MS, Tent \\
36 & Benzofluiazole & 2320 & 1.78 & 835 & 1981 & 1958 & RI, MS, STD \\
37 & 2-Phenylthiophene & 2476 & 1.76 & 780 & 2114 & 2124 & RI, MS, STD \\ \hline \hline \end{tabular}  
* RT1: retention time on the primary column.
* RT2: retention time on the secondary column.
* LRIcal: calculated linear retention indices.
* 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/))).
* 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 3: A total of 37 sulfides in Chinese herbaceous aroma-type Baijiu. A total of 17 lactone compounds were detected in the current study, of which 12 were identified in Baijiu for the first time. \(\gamma\)-Caprolactone and \(\gamma\)-nonalactone present weak sweet, fruity aroma in HAB [27].